Sequence of a cDNA coding for a rat class II Aαchain: Extensive DNA and protein sequence identity to H-2 Aαand HLA-DC1 α chains

✍ Scribed by Anne E. Wallis; W. Robert McMaster

• Publisher: Springer-Verlag
• Year: 1984
• Tongue: English
• Weight: 630 KB
• Volume: 19
• Category: Article
• ISSN: 0093-7711
• DOI: 10.1007/bf00364475

✦ Synopsis

The rat major histocompatibility complex (RT1-B region) codes for two sets of class II molecules (Ia antigens) referred to as A and E. Each class II molecule is composed of two glycoprotein chains called the A~ and Aa or E~ and E~. Two cDNA clones encoding rat A, chains were identified from cDNA derived from rat spleen mRNA using a combination of mRNA selection and colony hybridization techniques. The complete nucleotide sequence of the cDNA insert of one of these cDNA clones, pRIa.2, was determined. This sequence codes for the carboxy-terminal 129 amino acids of the rat A~ chain and 293 nucleotides of 3' untranslated sequence. The rat A~ chain was shown to be highly homologous in terms of both protein and DNA sequence identities to HLA-DC1 c~ and H-2 A~ chains. Comparison between the coding regions of the cDNA insert of pRIa.2 and the corresponding region of a cDNA insert encoding an HLA-DC1 e chain showed sequence identities of 85% and 81% at the protein and DNA levels, respectively. Comparison between pRIa.2 and cDNA encoding an H-2 A~ chain sequence showed identities of 91% for both protein and DNA. Results are discussed which strongly suggest that the class II A and E primordial genes arose by gene duplication prior to the evolutionary divergence of the mammals.