Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.1 (chymotrypsin)
10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of human red cell glycophorin A (GPA) on the expression of the human erythrocyte anion transporter (band 3, AE1) has been examined in Xenopus oocytes. The coexpression of GPA with band 3 increased stilbene disulfonate-sensitive chloride transport into the oocytes. The effect of GPA was particularly noticeable at low band 3 concentrations and less marked at high band 3 cRNA concentrations. The enhancement of chloride transport was specific to GPA and was not observed when either glycophorin B or glycophorin C was coexpressed with band 3. Immunoprecipitations of whole oocyte homogenates showed the amount of band 3 synthesized was not affected by GPA at subsaturating cRNA concentrations. More band 3 was detected at the oocyte surface by immunoprecipitation when GPA was also expressed. Chymotrypsin treatment of intact oocytes was also used to assess surface band 3 and greater cleavage of band 3 by chymotrypsin was observed when GPA was present. Band 3 synthesis and assembly into canine pancreatic microsomes in the reticulocyte cell-free translation system was not altered by cotranslation of GPA. We suggest that GPA facilitates the translocation of band 3 to the plasma membrane at some point during band 3 biosynthesis in Xenopus oocytes. However, GPA is not essential for the expression of band 3 in red cells, since GPA-deficient individuals have apparently normal levels of band 3. Other GPA-independent mechanisms must also allow translocation of band 3 to the surface membrane in erythroid cells and oocytes. GPA may affect the rate of accumulation of band 3 at the cell surface, rather than the final level in the plasma membrane.
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PMID:Glycophorin A facilitates the expression of human band 3-mediated anion transport in Xenopus oocytes. 138 95

Proteinase K-treatment of red blood cells either diminished or abolished the antigenic activities of glycophorin A and glycophorin B, and revealed the presence of a cryptic antigen that was recognized by antibody naturally existing in the autoplasma. About ninety five percent of all healthy persons have this autoantibody belonging to the IgM classification, whose titer ranges from 2 to 32. The activity of this autoantibody was absorbed by histidine and glutaminic acid. We were able to isolate this autoantibody from the plasma by means of an alkaline elution method and the autoantibody did not agglutinate chymotrypsin-treated red blood cells and red blood cells treated with chymotrypsin, following proteinase K-treatment. These results indicate that after proteinase K-treatment this autoantibody may not have an affinity for glycolipids, but for proteins digested by chymotrypsin.
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PMID:Blood group antigens transformed by proteinase K-treatment and the discovery of a natural autoantibody of these treated red blood cells. 223 30

Human anti-S and anti-s eluates bound to glycophorin B on immunoblots from membranes of S+ and s+ red cells, respectively. Eluates of human anti-S were more efficiently prepared from sensitized trypsin-treated cells than from sensitized untreated cells. The results of immunoblotting membranes from enzyme-treated cells confirmed the serological findings: S and s antigens were not affected by treatment with trypsin or sialidase but were destroyed or much depressed by treatment with papain, pronase or alpha-chymotrypsin. Immunoblotting with anti-S or anti-s of membranes from cells with unusual MNS phenotypes confirms the involvement of glycophorin B in hybrid glycophorins; the existence of such hybrid glycophorins was deduced previously from serological work or immunoblotting with monoclonal antibodies. The presence of s-active glycophorin B in glycophorin (B-A)Dantu, in glycophorin BMiIII and in glycophorin (A-B)MiV was confirmed. The bands observed when Mit+ membranes were immunoblotted with anti-S supports the suggestion from serological work that the Mit antigen is associated with an altered S antigen.
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PMID:Immunoblotting of human red cell membranes: detection of glycophorin B with anti-S and anti-s antibodies. 239 72

When red cells (RBCs) are treated with papain, one form of the U antigen, which we have named UPS (U papain-sensitive), is almost completely removed or denatured. A second form, UPR (U papain-resistant), remains unaltered on the treated RBCs. Tests on 42 examples of anti-U showed that two contained only anti-UPS, 19 contained only -UPR, and 21 contained separable -UPS and -UPR. In those sera containing both antibodies, anti-UPR was always the stronger of the two. These findings suggest 1) that UPS is located on the Ss sialoglycoprotein (glycophorin B) at a position distal to a papain-sensitive site or that the cleavage point is within the portion of the SGP that comprises UPS, and 2) that UPR is located between the papain-sensitive site and the RBC membrane. The UPS determinant was not denatured by neuraminidase, L-cysteine, trypsin, ficin, or alpha-chymotrypsin, and it was only partially denatured by pronase. The finding that RBCs treated with para-chloromercuribenzoic acid or para-chloromercuriphenyl sulfonic acid did not react with anti-UPR but did continue to react with anti-UPS suggests that the in situ configuration of UPR, but not UPS, is dependent on the presence of one or more disulfide bonds. RBCs of the S-s-U+(weak) phenotype were shown to carry markedly reduced amounts of both UPS and UPR.
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PMID:Heterogeneity of anti-U demonstrable by the use of papain-treated red cells. 274 73

The hybrid glycophorin in Dantu-positive human erythrocytes of the N.E. variety was not cleaved by treatment of intact cells with various proteases, in contrast to normal glycophorins. Therefore, it could be purified by phenol/saline extraction of membranes from trypsin-treated and chymotrypsin-treated red cells and subsequent gel filtration in the presence of Ammonyx-LO. The complete structure of the hybrid molecule, comprising 99 amino acid residues, was elucidated by sequence analyses of peptides prepared by chymotrypsin, trypsin, cyanogen bromide or V8 proteinase treatment. The N-terminal 39 residues and the glycosylation of the molecule were found to be indistinguishable from those of blood-group-s-specific glycophorin B. Conversely, the residues 39-99 were shown to be identical with the residues 71-131 of the major blood-group M-active or N-active sialoglycoprotein (glycophorin A). Hemagglutination inhibition assays revealed that the Dantu antigen represents a labile structure. The receptor might be located within the residues approximately 28-40 of the hybrid glycophorin, as judged from the effects of modifications of membranes. Our data provide an explanation for the previous findings that Dantu-positive cells (N.E. type) exhibit a protease-resistant N antigen and a qualitatively altered s antigen.
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PMID:Hybrid glycophorins from human erythrocyte membranes. I. Isolation and complete structural analysis of the hybrid sialoglycoprotein from Dantu-positive red cells of the N.E. variety. 359 15

Human red cells from donor Pj carry the Sta blood group antigen and an unusual sialoglycoprotein of 24 kDa molecular mass tentatively identified as a hybrid molecule of the anti-Lepore type [Blanchard et al. (1982) Biochem. J. 203, 419-426]. This component is resistant towards proteinase treatment and was purified from trypsin-treated and chymotrypsin-treated Pj erythrocytes. The molecule is composed of 99 amino acid residues whose alignment was established following manual and automatic sequencing of cyanogen bromide, trypsin, chymotrypsin and V8 proteinase peptides. The polypeptide chain comprises residues 1-26/28 of glycophorin B and residues 59/61-131 of glycophorin A. The sugar composition resembles that of glycophorin B, indicating the absence of an N-glycosidic chain. Identical sequences were obtained from analyses of the 24-kDa component purified from unrelated St(a+) donors. These results support the hypothesis that glycoprotein Pj represents a B-A hybrid molecule which is encoded by a new gene product resulting from an unequal crossing-over between the genes coding for the polypeptide chains of the glycophorins A and B. The novel molecule carries both N and Sta blood group antigens. The N activity is clearly understandable from the sequence of the five N-terminal residues (Leu and Glu at positions 1 and 5 respectively). Inhibition studies with the untreated and chemically modified hybrid glycoprotein indicate that the Sta determinant is located within residues approximately 25-30 of the molecule, which corresponds to the newly formed sequence found neither in glycophorin A nor in glycophorin B.
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PMID:Hybrid glycophorins from human erythrocyte membranes. Isolation and complete structural analysis of the novel sialoglycoprotein from St(a+) red cells. 362 21

Human erythrocytes with a deficiency in glycophorin A (En(a-) cells) and glycophorin B (S-s-U- and S-s-U+ cells) show significant resistance in vitro to invasion by Plasmodium falciparum merozoites. Treatment of normal erythrocytes with trypsin and chymotrypsin also reduced invasion. Trypsinization of S-s- and En(a-) red cells, a process which removes the T1 peptide of glycophorins A and C, produced cells almost refractory to invasion. The human K562 erythroleukaemia cell line, which also expresses glycophorin A, was not invaded and possible explanations for this result are discussed. It is suggested that determinants carried on the red cell sialoglycoproteins (glycophorins A, B and C), in particular the T1 peptide of glycophorins A and C, play an essential role in attachment and invasion by P. falciparum merozoites. The oligosaccharide components found on this peptide may play a role in the initial binding between red cell and merozoites.
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PMID:Erythrocyte sialoglycoproteins and Plasmodium falciparum invasion. 635 6

We have produced the murine monoclonal antibody (MAb) NaM70-3C10 (IgM) from splenocytes of mice immunized with human red blood cells (RBCs). The MAb agglutinated untreated as well as trypsin, chymotrypsin, neuraminidase, or ficin-treated RBCs from controls. In contrast, control RBCs treated with papaine or bromelaine were not agglutinated. On immunoblots, the MAb bound to glycophorin A (GPA) and to a 80 kDa protein identified as protein 4.1. Analysis by agglutination of variant RBCs carrying hybrid glycophorins made of the N-terminus (amino acids 1-58) of GPA and of the C-terminus (amino acids 27-72) of glycophorin B (GPB) and competition-inhibition test using purified GPA and a synthetic peptide corresponding to the amino acid sequence 48-58 of GPA demonstrated that the epitope is located within residues 48-58 of GPA. Epitope analysis with immobilized peptides showed that the MAb recognizes the sequence 53Pro-Pro-Glu-Glu-GIu58 of GPA. A homologous sequence is also present within amino acids 395 to 405 of protein 4.1. Finally, the MAb bound to 16 kDa chymotryptic peptide of protein 4.1, which carries the above amino acid sequence. In conclusion, it may be assumed that NaM70-3C10 specifically recognizes a common epitope on the extracellular domain of GPA and on the intracellular protein 4.1; this specificity explains the persistence of the 80 kDa band on blots when RBCs are treated with papain.
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PMID:Shared epitopes of glycoprotein A and protein 4.1 defined by antibody NaM10-3C10. 970 31

The recognition and invasion of human erythrocytes by the most lethal malaria parasite Plasmodium falciparum is dependent on multiple ligand-receptor interactions. Members of the erythrocyte binding-like (ebl) family, including the erythrocyte binding antigen-175 (EBA-175), are responsible for high affinity binding to glycoproteins on the surface of the erythrocyte. Here we describe a paralogue of EBA-175 and show that this protein (EBA-181/JESEBL) binds in a sialic acid-dependent manner to erythrocytes. EBA-181 is expressed at the same time as EBA-175 and co-localizes with this protein in the microneme organelles of asexual stage parasites. The receptor binding specificity of EBA-181 to erythrocytes differs from other members of the ebl family and is trypsin-resistant and chymotrypsin-sensitive. Furthermore, using glycophorin B-deficient erythrocytes we show that binding of EBA-181 is not dependent on this sialoglycoprotein. The level of expression of EBA-181 differs among parasite lines, and the importance of this ligand for invasion appears to be strain-dependent as the EBA-181 gene can be disrupted in W2mef parasites, without affecting the invasion phenotype, but cannot be targeted in 3D7 parasites.
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PMID:A novel erythrocyte binding antigen-175 paralogue from Plasmodium falciparum defines a new trypsin-resistant receptor on human erythrocytes. 1255 70

MNS antigens are carried on glycophorin A (GPA), glycophorin B (GPB), or their variants. Antigens at the N-terminus of GPA are sensitive to cleavage by ficin, papain, and trypsin but are resistant to alpha-chymotrypsin. Antigens at the N-terminus of GPB are sensitive to cleavage by ficin, papain, and alpha-chymotrypsin but are resistant to trypsin treatment. These characteristics have been used to aid in the identification of blood group alloantibodies. Recent molecular analyses have identified changes in amino acids that are associated with several low-incidence antigens in the MNS blood group system. This review relates the molecular studies with the susceptibility or resistance of these antigens to treatment of intact red blood cells by proteolytic enzymes.
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PMID:Low-incidence MNS antigens associated with single amino acid changes and their susceptibility to enzyme treatment. 1537 83


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