An Asp8Asn substitution results in the adenosine deaminase (ADA) genetic polymorphism (ADA 2 allozyme): occurrence on different chromosomal backgrounds and apparent intragenic crossover
作者:
R. HIRSCHHORN,
D. R. YANG,
A. ISRANI,
期刊:
Annals of Human Genetics
(WILEY Available online 1994)
卷期:
Volume 58,
issue 1
页码: 1-9
ISSN:0003-4800
年代: 1994
DOI:10.1111/j.1469-1809.1994.tb00720.x
出版商: Blackwell Publishing Ltd
数据来源: WILEY
摘要:
SUMMARYWe have now determined the molecular genetic basis for the common biochemical polymorphism at the adenosine deaminase (ADA) locus. The ADA*2 allele contains a G to A transition at nt22 (relative to the ATG) that results in substitution of asparagine for aspartic acid at codon 8 (Asp8Asn). Introduction of the nucleotide substitution into an ADA 1 cDNA and transfection into monkey kidney (Cos) cells confirmed that the mutation resulted in expression of an enzyme that comigrated with the naturally occurring ADA 2 allozyme. The substitution of neutral asparagine for anionic aspartic acid is consistent with the more cathodal electrophoretic migration of ADA 2 as compared with ADA 1. The nucleotide substitution was found on at least two different genetic backgrounds, suggesting independent recurrence of the mutation. Consistent with independent recurrence, the G to A transition is at a CpG dinucleotide and represents a type of mutation that occurs with high frequency. We have also unexpectedly identified a probable intragenic crossover in the very large first intron that is rich in repetitive DNA sequences.
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