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Query: UMLS:C0272170 (SDS)
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A series of 38 primary laryngeal and hypopharyngeal tumours, 15 lymph-node metastases and normal tissue were evaluated in frozen sections for the expression of MHC class I and II antigens, using monomorphic monoclonal antibodies (MAbs) to HLA-ABC, beta 2-microglobulin, DR, DP, DQ, HLA-B and polymorphic HLA-ABC antigens. Normal distant mucosa of larynx reacted to anti-class I antibodies but not to anti-class II. In 9 primary tumours (23.7%) HLA class I antigens were not observed. The remaining 29 showed a strong reaction to not observed. The remaining 29 showed a strong reaction to anti-HLA-ABC (heavy chain) and anti-beta 2-microglobulin, although in 3 cases out of 29 no staining was observed with anti-HLA-B locus-specific MAbs. These selective losses were confirmed using the corresponding anti-HLA polymorphic MAbs. For HLA class II molecules, only DR was observed in 3 of 38 cases. Defective HLA class I expression statistically correlates with high scores according to Jakobsson's criteria for histopathological tumour grading. Loss of HLA-ABC antigens was most frequent among the cases with poor differentiation (6/8 cases). On the contrary, class II antigen expression was correlated with a well differentiated pattern and a more favourable prognosis (p less than 0.001). We have found differences in HLA class I expression when comparing primary tumours and autologous metastases (3/9 cases). Immunoprecipitation and SDS-PAGE of class I antigens, Northern and Southern blot analyses of MHC class I genes were performed. We have not detected class I gene rearrangement using HLA coding and locus-specific non-coding probes. However, we have found a class I transcription defect that corresponds with a class-I-negative phenotype.
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PMID:Histocompatibility antigens in primary and metastatic squamous cell carcinoma of the larynx. 264 39

Detection of the beta 2-microglobulin (beta 2m) component of the rat MHC class I antigens has been difficult. In the present report, we have addressed this issue by a systematic study of rat class I antigens from red blood cells or from lymphocytes that were freshly isolated or cultured in the presence of autologous or heterologous sera and surface-labeled with 125I or intrinsically labeled with radioactive amino acids. First, specific radioiodination of rat beta 2m in association with the antigen heavy chain on red blood cells or lymphocytes is minimal, resulting in its poor identification by SDS-PAGE. Second, labeling with radioactive methionine or lysine gives a more intense beta 2m band with respect to the heavy chain than labeling with arginine or tyrosine. Third, the beta 2m component shows a large increase in intensity compared to the heavy chain when the antigens are isolated from lymphocytes that are cultured in the presence of fetal bovine serum prior to 125I-labeling. This increase is due to exchange of endogenous rat beta 2m with bovine beta 2m and to a much higher level of radioiodination of the latter. Fourth, rat red blood cells and lymphocytes contain free surface beta 2m molecules in addition to those associated with the antigen heavy chains. The free molecules show a much higher level of radioiodination than those associated with the heavy chains, and there is little exchange between the antigen-bound and the free beta 2m after radioiodination.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Beta-2-microglobulin of rat major histocompatibility complex class I antigens. 266 96

Investigations into the mechanisms by which Ig in human colostrum influence the development and maturation of both the gastrointestinal and the immune systems of human milk-fed term and preterm infants have been restricted by the paucity of purified human milk Ig. We have developed a simple adsorption procedure for the selective removal and quantitative recovery (95-100%) of intact Ig (secretory IgA, IgG, and IgM) present in human colostral whey. The procedure exploits the rapid, ionic-strength dependent, thiophilic adsorption of Ig during a single pass of colostral whey through a column of beaded agarose with immobilized thioether-sulfone ligands (Anal Biochem 1986;159:217-226). The purity and composition of the adsorbed Ig were verified by SDS-PAGE and sensitive silver-staining protein detection procedures; proteins of approximately 78-80 kD (secretory component), 50-60 kD (heavy chain), and 25 kD (light chain) were observed. The identity, structural integrity, and relative concentrations of the recovered Ig were confirmed by high-performance size-exclusion chromatography, Ouchterlony immunodiffusion, rocket immunoelectrophoresis and ELISA. These results were analyzed and compared with reported values for the concentration of human milk Ig. Thus, the use of thiophilic adsorption appears to facilitate 1) selective removal of Ig from colostrum, enabling the evaluation of remaining components for growth- and immune-potentiating properties, and 2) selective immobilization and recovery of Ig from colostrum under conditions consistent with preserved biologic activity.
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PMID:Selective removal, recovery, and characterization of immunoglobulins from human colostrum. 268 87

Tetanus toxin, as obtained from bacterial culture filtrates, consists of two chains. Since their roles in poisoning are unknown, we have made a detailed study of their preparation, reassociation and pharmacological activity. 1. Two-chain tetanus toxin (pI 6.0) was subjected to isoelectric focussing under reducing conditions in 2M urea. Both light (pI 4.8) and heavy (pI 7.2) chains separated as nearly homogeneous proteins of low toxicities. Upon removal of urea and reoxidation, partial homodimerization by formation of disulfide bonds took place in the purified fractions. The toxin was reconstituted nearly quantitatively by covalent heterodimerization of the complementary chains, as shown by SDS/gel electrophoresis, toxicity studies, inhibition of evoked [3H]noradrenaline release and binding to rat brain membranes. 2. Accordingly, fragment B (pI 5.6) resulting from papain hydrolysis, was separated into a light chain and the N-terminal moiety of the heavy chain, called fragment beta 2 (pI 7.1 and 6.8, two maxima). Removal of urea and reoxidation led to reconstitution of fragment B. Covalent linkage did not occur between the two parts of the heavy chain, or between the light chain and the C-terminal part of the heavy chain. 3. The heavy chain alone inhibited K+-evoked [3H]noradrenaline release from a rat brain homogenate. However, the concentration-response ratio was flat and 10-100-fold higher concentrations were required than with native or reconstituted two-chain toxin. The light chain was inactive. Purified heavy chain but not light chain decreased the [3H]noradrenaline content, whereas the two-chain toxin increased it. Binding to rat brain membranes was assessed by competition with 125I-labelled two-chain toxin. In hypotonic buffer, the heavy chain, the papain fragment C and native and reconstituted two-chain toxin had comparable affinities to membranes. In isotonic buffer the heavy chain displayed an about 1000-fold lower affinity than native or reconstituted two-chain toxin. The light chain did not bind to membranes in either test. Our data indicate that (a) the light chain and the N-terminal part of the heavy chain are held together not only by one disulfide bond but also by hydrogen bonds and ionic forces to yield a two-chain toxin or fragment B and (b) both chains contribute to the actions of the toxin in vivo and in vitro, and to its binding.
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PMID:Chains and fragments of tetanus toxin. Separation, reassociation and pharmacological properties. 275 37

Changes in the expression of heavy chains of myosin during development determine the functional characteristics of striated muscles. The distribution of heavy-chain isoforms of smooth-muscle myosin was determined in the airways of adult and infant humans to see whether it might underlie the hyperreactivity of human airways. The protein bands corresponding to myosin were separated using SDS/polyacrylamide-gel electrophoresis (4% gels) and identified by immunoblotting using both monoclonal and polyclonal antibodies against smooth-muscle myosin and non-muscle myosin. The relative proportion of each heavy chain stained by Coomassie Blue was measured by densitometric scanning. Three major bands corresponding to myosin heavy-chain isoforms were found; the two slower migrating bands (MHC1 and MHC2) were smooth-muscle myosin, and the third band was non-muscle myosin. The MHC1/MHC2 ratio was 0.69:1 in adult bronchus, and in infant bronchus and trachea. This contrasted with the airway smooth muscle in pigs, which was run concurrently, where the smooth-muscle heavy-chain ratio changed with development [Mohammad & Sparrow (1988) FEBS Lett. 228, 109-112]. The non-muscle myosin heavy chain comprised 63% of the smooth-muscle myosin. In both adult and infant lungs an additional putative myosin heavy chain which migrated slightly more rapidly than non-muscle myosin heavy chain was identified using the monoclonal smooth-muscle myosin antibody BF 48. This was unique to the human species.
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PMID:The distribution of heavy-chain isoforms of myosin in airways smooth muscle from adult and neonate humans. 276 80

We have isolated and purified an activity from amoebae of Physarum polycephalum that reduces the flow birefringence of a solution of F-actin in a Ca2+-dependent manner. The purified activity from 100 g of amoebae consisted of 1 mg of a 40,000 mol. wt protein. DNase I-affinity chromatography demonstrated that the protein binds to Physarum actin in a Ca2+-dependent manner, and the binding is not reversed by excess EGTA. Viscometric measurement indicated that the protein (i) accelerates polymerization of G-actin, and (ii) severs F-actin, in a Ca2+-dependent manner. Thus, the protein appeared functionally similar to the fragmin previously isolated from Physarum plasmodia (plasmodial fragmin). However, the two proteins had slightly different mobilities on urea-SDS-PAGE, and antibodies raised against the two proteins scarcely cross-reacted with each other. Hence, we conclude that the two proteins are closely related to but are different from each other, and we have named the novel protein 'myxamoebal fragmin'. Immunoblot analysis indicated that myxamoebal and plasmodial fragmins are specifically present in amoebae and plasmodia, respectively. Results of immunofluorescence staining suggest that the synthesis of plasmodial fragmin is switched on coordinately with the synthesis of the heavy chain of plasmodial myosin and other plasmodium-specific contractile proteins during the apogamic differentiation of amoebae to plasmodia.
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PMID:Purification of myxamoebal fragmin, and switching of myxamoebal fragmin to plasmodial fragmin during differentiation of Physarum polycephalum. 284 75

Acrosin purified from an acidic extract of ejaculated goat spermatozoa migrated as a single 42,000-Mr band in SDS/polyacrylamide-gel electrophoresis. Reduction and alkylation of caprine acrosin produced two polypeptides, one of Mr 40,000 (heavy chain) and the other of Mr 3700 (light chain). The light chain purified by reversed-phase h.p.l.c. was a glycosylated octadecapeptide with an amino acid sequence similar to that of the N-terminal 18 residues of porcine acrosin light chain (78% positional identity). The sequence of the N-terminal 37 amino acids of purified caprine acrosin heavy chain is similar to that of porcine acrosin heavy chain (70% positional identity through 37 residues). Studies with synthetic substrates and synthetic and natural proteinase inhibitors confirmed both the specificity of the purified proteinase for Arg-Xaa and Lys-Xaa bonds and a serine-proteinase mechanism. Purified caprine acrosin hydrolysed the 90 kDa and 65 kDa components, but did not hydrolyse the 55 kDa component of the porcine zona pellucida. The action of the enzyme on the porcine zona pellucida was indistinguishable from that previously reported for porcine acrosin.
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PMID:Caprine acrosin. Purification, characterization and proteolysis of the porcine zona pellucida. 293 Apr 60

Chymotryptic digestion of scallop myosin yielded two different preparations of subfragment-1, having the following features. The major product from chymotryptic digestion of scallop myosin was subfragment-1 (S1) either in Ca-medium or in EDTA-medium. However, the S1 preparations obtained from the digestion in Ca-medium, abbreviated as Ca-S1(CT), had both types of light chain subunits (regulatory light chains (R-LC) and essential light chains (SH-LC], and 100 Kdaltons (Kd) heavy chain subfragments (HCs), whereas the S1 preparations obtained from the digestion in EDTA-medium, ED-S1(CT), had no R-LC, partially fragmented SH-LC (SH-LC), and 90 Kd HCs. On the other hand, Ca-S1(CT) and ED-S1(CT) were practically identical with each other in ATPase activity and in actin-binding ability. The two S1 preparations were also identical in that the Mg-ATPase activity of both S1 and acto-S1 was insensitive to calcium ions. Ca-S1(CT), which contained both R-LC and SH-LC in a stoichiometric amount, was further digested with trypsin, which is known to cleave rabbit skeletal myosin not only at the head-tail junction but also in the head. The tryptic digestion of Ca-S1(CT) appeared, in terms of the SDS-gel electrophoretic pattern, to occur at a much faster rate in Ca-medium than in EDTA-medium, and with a different digestion profile. It is therefore suggested that association of R-LC induces changes in the heavy chain conformation which result in an increase in the proteolytic digestibility of heavy chains and in an alteration of the site of proteolytic cleavage on heavy chains.
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PMID:Two different preparations of subfragment-1 from scallop adductor myosin. 293 24

The biochemical properties of 21S dynein derived from sea urchin sperm flagella and of its components dissociated by low salt treatment were studied. SDS-urea gel electrophoresis and two-dimensional gel electrophoresis showed that the 21S dynein preparation contains two distinct heavy chains. These two heavy chains, termed A alpha and A beta, had apparently the same molecular weight of 500,000 but showed different mobilities on SDS-urea gels. The isoelectric points of A alpha and A beta heavy chains were 5.7 and 5.2, respectively, in the presence of urea. Proteolytic digestion patterns of these two heavy chains were clearly different, but the amino acid compositions were similar. Low salt treatment and sucrose density gradient centrifugation could partially separate the components of 21S dynein into two fractions: the one with larger sedimentation coefficient contained the A alpha heavy chain, and the other with smaller sedimentation coefficient contained the A beta heavy chain and three intermediate chains. These two fractions showed distinctly different kinetic properties, and thus may play different roles in dynein-microtubule interaction.
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PMID:Two heavy chains of 21S dynein from sea urchin sperm flagella. 293 25

Scallop S1 has a region sensitive to tryptic hydrolysis not found thus far in S1s of other species, located 65K from the N-terminus as determined by SDS/polyacrylamide-gel electrophoresis. In the presence of actin the S1 heavy chain is preferentially cleaved at this site. The high-salt EDTA and calcium ATPase activities of the nicked 65K-31K S1 are abolished. This inactivation is not due to denaturation, conformational effects of actin, or to light chain dissociation. The unique proteolytic site of scallop S1 is adjacent to a peptide involved in actin-S1 interaction in scallop and rabbit but it is far removed from the nucleotide-binding site in the linear amino acid sequence. We conclude that proteolysis inactivates the high-salt ATPase activities through a connection mediated by tertiary interactions. Such a connection provides a structural correlate for the known reciprocal relationship between the nucleotide and actin affinities of myosin.
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PMID:An intact heavy chain at the actin-subfragment 1 interface is required for ATPase activity of scallop myosin. 295


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