Article Abstract:
Experimental studies of the somatic hypermutation of light chain V genes in the ileum of germ-free sheep, in thymectomized animals and in sterile ileum fragments isolated from gut reveal that the accumulation of the mutations on the genes is independent of external antigens and that the pattern of the mutations is similar in all the three experimental and in the control tissues. The hypermutation process targets the replacement mutations in the complimentarity-determining regions. The major V-lambda genes display codon usage specificity with high purine levels at the first two codon bases and low purine levels at the third base.
User Contributions:
Comment about this article or add new information about this topic:
Article Abstract:
Mice deficient in major histocompatibility complex (MHC) molecules I and II were analyzed to determine T cell specificities in the absence of MHC expression. Analysis of the MHC reactivity of germline T cell receptor (TCR) sequences indicated the presence of inherent MHC reactivity in TCRs due to the specific interaction of the receptors with MHC. Coreceptor signaling induced by anti-CD4 antibody promoted positive selection in a manner that was similar to MHC-mediated positive selection in vivo. Furthermore, the preselection repertoire exhibited high reactivity with MHC-expressing cells.
User Contributions:
Comment about this article or add new information about this topic:
Article Abstract:
Mutations of the XH2 gene cause the ATR-X syndrome. Mutant XH2 appears to down-regulate expression of several genes, suggesting that it is a global transcriptional regulator. XH2 belongs to the SNF2 subgroup of a helicase superfamily, and may be involved in other disorders stemming from Xq13 abnormalities.
User Contributions:
Comment about this article or add new information about this topic: