Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously found that the inhibitory effect of hemoglobin F (Hb F) on the polymerization of Hb S proceeds via the formation of asymmetrical hybrid tetramers of the type alpha2betasgamma. Examination of the gelling properties of binary mixtures of Hb S and several Hb variants now shows that, among the gamma chain amino acid residues that differ from those of the beta chain, residues gamma80 (EF4) and gamma87 (F3) are at least partly responsible for this inhibition. Furthermore, we find that mixing Hb A2(alpha2delta2) with Hb S strongly inhibits gelling to an extent similar to that seen with Hb S/Hb F mixtures; this inhibition is attributable to amino acid differences between the delta and beta chain sequences at positions delta22 (B4) and delta87 (F3). Therefore, residues 22, 80, and 87 of the beta chain appear to be involved in intermolecular contact sites that stabilize the deoxy Hb S polymers.
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PMID:Structural bases of the inhibitory effects of hemoglobin F and hemoglobin A2 on the polymerization of hemoglobin S. 28 92

A selective CD3 gamma defect, involving point mutations in both the paternal and the maternal genes, has been analyzed. The CD3 gamma defect affected two brothers of a four sibs family; one of them died at the age of 3 of a viral pneumonia with concomitant autoimmune features (Haemolytic anaemia and gut epithelial cell autoantibodies), whereas the other is still alive at the age of 10 with relatively mild infection episodes. In this work, the effects of the absence of the CD3 gamma chain in the structure and signal transduction of the T-cell receptor (TCR)/CD3 complex and in the selection and function of T lymphocytes were studied. The absence of CD3 gamma did not prevent the expression of certain amounts of TCR/CD3 complexes on the surface of T lymphocytes. This suggests the existence of at least two TCR/CD3 isoforms in T cells, either with or without CD3 gamma. A persistent low proportion of CD8+ T cells, not functional in vitro (they were unable to proliferate) and probably in vivo (associated to a lethal viral pneumonia), was observed. In contrast, the proportion of CD4+ T cells was not altered, and they were functional both in vitro (they showed a normal proliferation and a low, but detectable, increase of cytosolic Ca2+ in response to anti-TCR/CD3 stimuli, although the production of IL-2 was impaired) and in vitro (they normally helped B cells). These results show that the absence of CD3 gamma affects the selection and function of cytotoxic, but apparently not helper, T lymphocytes, although the possibility that the CD4+ T cells represent a specific subpopulation can not be ruled out. They also suggest that the interactions of the TCR/CD3 complex with its co-receptors during thymic selection and antigen recognition in the periphery may be asymmetrical, with CD8 interacting through CD3 gamma and, probably, CD4 through the homologous CD3 delta.
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PMID:T lymphocyte signalling defects and immunodeficiency due to the lack of CD3 gamma. 790 75