Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A novel Ig-binding protein has been isolated from the surface of bacteria belonging to the anaerobic species Peptococcus magnus. To solubilize the protein, peptococci were treated with different proteolytic enzymes (papain, pepsin, and trypsin) or with mutanolysin, a bacteriolytic agent known to digest the cell walls of streptococci. Papain, trypsin, and mutanolysin all solubilized peptides showing affinity for radiolabeled human IgG in Western blot analysis. Compared with papain and trypsin, mutanolysin liberated a more homogeneous material, which also had a higher m.w. This mutanolysin-solubilized protein (Mr 95 kDa) was obtained highly purified by a single isolation step on IgG-Sepharose, and the molecule was found to exhibit unique Ig-binding properties. Thus, in dot blots and in Western blots, human IgG, F(ab')2 and Fab fragments of IgG, and human kappa and lambda L chains all showed affinity for the protein. Moreover, the molecule also bound human IgM and IgA, whereas no binding was recorded for IgG-Fc fragments or IgG H chains. Finally, the protein bound to human polyclonal Ig L chains immobilized on polyacrylamide beads. These different data demonstrate that the isolated peptococcal protein binds Ig through L chain interaction. The name protein L is therefore suggested for this novel Ig-binding bacterial cell wall protein.
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PMID:Protein L. A novel bacterial cell wall protein with affinity for Ig L chains. 312 50

Streptococci of serological groups A, B, C, G and L were examined for interactions with human colostral IgA. Of 28 A-streptococcal cultures, 12 bound IgA with a mean of 38.7%. The other streptococci had little or no IgA-binding activities. Of the 12 IgA-binding A-streptococcal cultures, 8 contained the M-protein M 4 and 2 the M-protein M 60. The specific binding sites for IgA were heat-sensitive (60 min, 80 degrees C) and susceptible to trypsin and pronase.
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PMID:Interactions of streptococci with human colostral immunoglobulin A. 318 Jul 27

The protecting effect of human milk against intestinal infections has been well documented, but its mechanism not completely understood. We have examined the effect of the nonimmunoglobulin fraction (NIgF) of human milk and colostrum on bacterial adherence to the intestinal tract. The NIgF was prepared by passing the milk through an immunosorbent column containing rabbit antihuman gamma-globulin (IgG and IgA). The effluent fraction did not contain gamma-globulins as shown by immunodiffusion on agarose and by using rabbit antihuman Ig, that was then detected with fluorescently-labeled goat antirabbit Ig. The effect of the NIgF of human milk on the adherence of enterotoxigenic Escherichia coli strains to guinea pig intestinal tract was quantitatively determined using radiolabeled bacteria which were incubated with suspensions of viable intestinal cells. Thirteen to 17 bacteria adhered per intestinal cell. NIgF of human milk and colostrum (300 microliter, 6.7 mg) caused about 50% inhibition of the adherence of enterotoxigenic E. coli strains whose attachment was mediated by colonization factor antigen I and II. No inhibition was noted on the adherence of enterotoxigenic E. coli strains containing type I pili. The inhibitory activity resisted boiling and proteolytic digestion with trypsin, but was completely abolished by periodate treatment, indicating that carbohydrate residues were probably involved. Examination of the effect of NIgF of human milk on bacterial adherence to intact intestinal surfaces revealed comparable results. Observations with scanning electron microscopy confirmed, morphologically, the attachment of the bacteria and the inhibitory effect of human milk.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Nonimmunoglobulin fraction of human milk inhibits the adherence of certain enterotoxigenic Escherichia coli strains to guinea pig intestinal tract. 330 55

Bovine secretory component (SC) has been cleaved with trypsin into a series of fragments and their N-terminal amino acid sequences have been determined. The close homology with the known sequence of human SC has enabled the sequential order of the fragments to be deduced. The results indicate that bovine SC consists of a single glycosylated polypeptide chain (Mr 74,000) folded into five globular immunoglobulin-like domains. A protein (Mr 94,000) has been isolated from detergent solubilised bovine epithelial membranes from liver, intestine and mammary gland. This membrane protein is specific for the binding of J-chain linked IgM and IgA dimers. It can be proteolytically cleaved into a water soluble SC-like portion and a detergent soluble hydrophobic portion. Bovine SC is therefore most likely to be the extracellular part of an epithelial receptor which mediates the transport of IgA dimers to mucosal surfaces. The various tryptic fragments from bovine SC have been shown to differ in their relative binding affinities for IgM and IgA dimers. The results imply that the first three domains of bovine SC are most involved in binding and domains 4 and 5 play subsidiary roles. Computerized prediction and modelling methods have been used to deduce possible tertiary and quaternary structures for SC. There are good indications that the molecule has an elonaged "zig-zag" structure stabilized by longitudinal inter-domain contacts. A model of SC bound to IgA dimer is presented.
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PMID:The structure of bovine secretory component. 343 66

In vivo labeling with [35S]cysteine has identified three transmembrane forms of the rat hepatic polymeric IgA receptor: (i) a 105-kDa core glycosylated precursor; (ii) a terminally glycosylated 116-kDa intermediate; and (iii) a mature 120-kDa form. In the current study we show that the 120-kDa form is phosphorylated. After in vivo labeling with [32P]orthophosphate, all receptor forms were immunoprecipitated from hepatic total microsomes (TM) (with an antireceptor antiserum), separated by NaDodSO4/PAGE, and detected by autoradiography. The 120-kDa form was selectively phosphorylated, whereas the 116- and 105-kDa forms incorporated no detectable 32P. To determine the topology of the phosphorylation sites, hepatic TM isolated from rats labeled in vivo with either [35S]cysteine or [32P]orthophosphate were treated with trypsin. TM were solubilized and receptors were immunoprecipitated from lysates. With increasing trypsin concentrations, the [35S]cysteine-labeled receptor triplet was degraded to a trypsin-resistant doublet of approximately 95 and 85 kDa, indicating that approximately 20 kDa was removed from the receptor endodomain by trypsin. The same treatment removed all detectable 32P from labeled receptors. Furthermore, no 32P was detected in the 80-kDa biliary form of the receptor. Serine was identified as the only phosphorylated residue in acid hydrolysates of 32P-labeled immunoprecipitated receptor. These findings indicate that (i) the 120-kDa form is the only phosphorylated species of the receptor; and (ii) the phosphorylated residues are serine(s) located in the endodomain of the protein.
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PMID:Phosphorylation of the rat hepatic polymeric IgA receptor. 346 69

Two mouse monoclonal antibodies generated against human placental homogenate were found to react specifically with human complement component C3. In immunofluorescence of human tissues, these antibodies gave a bright linear staining outlining the glomerular basement membrane of the adult kidney and the trophoblast basement membrane of placenta. An identical staining pattern was observed with a rabbit C3d antiserum which also prevented binding of the monoclonal antibodies to tissue sections. Only negligible basement membrane staining was observed in the same tissues with antisera to human C3c, C5, IgG, IgA, or IgM. When interactions of C3 with basement membrane proteins were tested in enzyme immunoassays and column chromatography, C3(H2O) was found to bind efficiently to solid-phase laminin. Native C3 from fresh plasma did not bind to laminin but C3 from plasma treated with methylamine bound efficiently. When C3 was cleaved with trypsin, C3b and C3d but not C3c bound to laminin-Sepharose. The interaction of C3 and laminin was inhibited by soluble laminin and by high ionic strength. The results indicate that C3d, a biologically active breakdown product of C3, can be found in glomerular and placental basement membranes in the absence of signs for ongoing local complement activation or immune complex deposition. It is possible that binding affinities between C3 and basement membrane molecules, especially laminin, are involved in the retention of C3d at these sites. Such interactions between C3 and components of the glomerular basement membrane could play important roles in complement-related pathological processes of the glomerulus.
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PMID:C3d fragment of complement interacts with laminin and binds to basement membranes of glomerulus and trophoblast. 348 95

We studied the mechanism of transport of proteins into the nucleus using synthetic peptides containing the nuclear location signal sequence of Simian virus 40 (SV 40) large T-antigen. When chick erythrocytes containing a synthetic large T-antigen nuclear translocation signal were fused with SV 40-transformed human fibroblasts, the migration of native large T-antigen into the chick nuclei was suppressed. Migration of proteins detected by human specific antinuclear autoimmune antibody was not blocked. An analog of the nuclear location signal peptide did not inhibit entry of large T-antigen into the chick nuclei. This result suggests that the peptide blocked the migration of only native large T-antigen into the nucleus, and that the signal of the majority of nuclear proteins for nuclear transport is not the same as that of the large T-antigen. The synthetic peptide was conjugated chemically with bovine serum albumin (BSA) and introduced into the cytoplasm of cultured human cells by red blood cell ghost-mediated microinjection. The BSA-synthetic peptide conjugate was found predominantly in the nucleus within 2 h after its introduction into the cells. BSA conjugated with the cross-linking reagent alone was not transported into the nucleus. Acetylated synthetic peptide was not effective in promoting nuclear localization of BSA. Mild trypsin treatment of the BSA-synthetic peptide conjugate suppressed nuclear localization. Conjugates of the synthetic peptide with phycoerythrin (Mr about 150 kD) and with secretory IgA (Mr about 380 kD) were both found in the nucleus very shortly after their introduction into the cytoplasm. These results suggest that the synthetic peptide containing the nuclear location signal sequence provides exogenous proteins with the ability to migrate into the nucleus. But, since a conjugate of the synthetic peptide with IgM (Mr about 940 kD) did not migrate into the nucleus after its microinjection, there may be a size limit in nuclear transport of conjugated proteins.
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PMID:Synthetic peptides containing a region of SV 40 large T-antigen involved in nuclear localization direct the transport of proteins into the nucleus. 359 38

The level of IgA-alpha 1 anti-trypsin (alpha 1 AT) complex in a relatively large number of IgA myeloma sera has been determined, and compared with their content of polymerised forms of IgA. The level of the complex was the same in sera containing only monomeric IgA, some polymer and more than 50% polymer (as determined by SDS-PAGE). There was, however, a highly significant inverse correlation between the amount of IgA-alpha 1 AT complex in the myeloma sera and their content of 10S dimer (as determined by analytical ultracentrifugation). High levels of IgA-alpha 1 AT complex were also found in the small number of myeloma sera examined which contained paraprotein of the minor allotypic form of (Am2+) of the IgA2 sub-class, indicating that the lack of disulphide bonds between the heavy and light chains of this isotype has no influence on its ability to complex with alpha 1 AT.
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PMID:Measurement of IgA-alpha 1 anti-trypsin (alpha 1 AT) complex in the sera of patients with IgA myelomatosis. 387 38

Primary central nervous system (CNS) lymphomas have been perceived as CNS counterparts of systemic non-Hodgkin's lymphomas (NHL). Their pathogenesis in respect to the cell of origin, however, has been controversial. A highly sensitive and specific immunoperoxidase method for cytoplasmic immunoglobulins (CIg) using anti-kappa and anti-lambda light-chain antisera in addition to antibodies against IgM, IgG, IgA and IgE heavy chains and J-chain was performed on 27 surgically removed and histologically confirmed primary CNS lymphomas. In order to increase the sensitivity, slides were treated with trypsin to expose the various CIg components. Results indicated that the majority of CNS lymphomas (20 cases or 74.01 percent) were negative for monoclonal CIg. Only four cases (14.81 percent) were definitely positive for CIg with monoclonal staining pattern. Results of the remaining three cases were inconclusive. Among those four cases with positive CIg, three were histologically identified as immunoblastic sarcomas according to the Luke-Collins classification. It is concluded that, in contrast to systemic NHL, primary CNS lymphomas are mostly negative for monoclonal CIg. Whether these CIg negative neoplasms are T and/or null cells in nature or whether they represent an unidentified group of neoplasms is not clear at the present.
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PMID:Immunoperoxidase study of primary central nervous system lymphomas. 390 73

In radiobinding tests many group A, C and G streptococci react with IgG and IgA, irrespective of the antigen-combining sites, as well as with various other serum proteins, e.g. human serum albumin (HSA). The present study demonstrated that glutaraldehyde-aggregated, radiolabelled HSA (a*HSA), in comparison to monomeric HSA, binds more avidly to streptococci. Of group A streptococci, strains representing types M6, M12, M18, M46, M55 and M57 displayed pronounced binding of a*HSA whereas a number of other serotypes were non-reactive. The streptococcal sites involved proved to be relatively heat-resistant and highly sensitive to trypsin treatment. Human fibrinogen counteracted the binding of a*HSA. The uptake by M12 was inhibited strongly by rabbit antiserum raised against M12, whereas other antisera were less active. The results suggest that the bacterial structure binding a*HSA is a protein and that, in at least one serotype, M12, the binding occurs to the M-protein.
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PMID:Binding of aggregated human serum albumin to M12 and some other types of group A streptococci. 392 62


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