Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.108 (TAT)
 2,389 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

HLA-B27 is a human major histocompatibility complex class I product defined by its antigenic specificity with conventional alloantisera. Detailed studies using monoclonal antibodies, cytotoxic T lymphocytes (CTL), and isoelectric focusing (IEF) gel electrophoresis demonstrated the heterogeneity in the B27 antigen. We have previously identified a unique variant molecule of B27 designated locally as B27d which is distinguished from other B27 variants by isoelectric point, serologic reactivity, and by a cloned CTL recognition. A gene encoding the B27d variant has been cloned and a complete nucleotide sequence has been determined. Compared to the sequence of the prototype B27a, the B27d has a single base substitution at codon 59 (B27a:TAT--B27d: CAT) in exon 2 responsible for Tyr to His substitution. A His residue at this position in the alpha 1 domain is unique among the known class I sequences and this single amino acid change is apparently sufficient to alter the epitope(s) recognized by antibody and cytotoxic T cell receptor. Previous primary structural analysis of the other five B27 variants has revealed differences of two to four amino acids. The combined structural data on the B27 variants indicate that (1) HLA-B27 represents a family of closely related B locus alleles that share the B27 allospecificity and differ by a limited number (one to four) of amino acid substitutions and (2) point mutation as well as gene conversion might be the mechanism responsible for the allelic variation of B27 antigen family.
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PMID:Molecular analysis of the variant alloantigen HLA-B27d (HLA-B*2703) identifies a unique single amino acid substitution. 328 82

A new HLA-B18 allele (B*1802) derived from a Thai individual was sequenced. Comparison of this B18 nucleotide sequence with the published B*1801 sequence indicated that this Asian B18 allele has a nucleotide sequence different from that of B*1801. Three nucleotide changes were observed in exon 3, in which two substitutions at codon 97, AGG in B*1801 to AAT in the B*1802, result in an amino acid change from arginine to asparagine. The residue 97Asn has also been described in some B27 subtypes. A silent mutation was also observed at codon 99, TAC in B*1801 to TAT in the B*1802. This sequence has been reported in many class I alleles published so far. Moreover, 18 HLA-B18-positive samples were examined by the PCR-SSO method using specific probes for B*1801 and B*1802. The results demonstrated that three Asian samples possess B*1802 and share HLA-Cw7, DR12, and DQ7.
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PMID:A new B18 sequence (B*1802) from Asian individuals. 775 Nov 57