ISSN:
1744-313X
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
,
Medicine
Notes:
An attempt was made to characterize the amino acid interchanges in the presumably allelic products of MHC (H-2 and HLA) as revealed by the results published so far of microsequencing analysis of their 20-30 N-terminal positions. The distances between interchanged amino acids were judged by several criteria: the Sneath's and Grantham's indices, the classification of the substitutions as intra-versus intergroup (i.e. groups of chemically related amino acids), the minimum number and type of underlying base substitutions according to the genetic code. The detected variation was also compared to that in highly variable (fibrinopeptides A and B) and highly conservative (histone IV) amino acid sequences. A selection of human haemoglobin α-chain variants, without known pathological effects, was further used as a standard of reference for intraspecific ‘permissible variation'. The results of these comparisons do not prove, but are not incompatible with, the idea that the function of the H-2 (HLA) fragment displaying the observed molecular variability, does not impose too rigid a constraint on its structure. Considerably different amino acid sequences might represent functionally more or less equivalent compromises due to neutral mutations which fall into the category of ‘evolutionary noise’ at the molecular level.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1744-313X.1979.tb00688.x
