TRANSPORT-ASSOCIATED PROTEINS IN ATLANTIC SALMON (SALMO-SALAR)

The major histocompatibility complex (Mhc) regions of mice, rats, and humans all contain a pair of related genes, TAP1 and TAP2, which encod e members of a large superfamily of proteins of similar structure and function. A functional TAP1/TAP2 heterodimer is probably required for efficient presentation of antigens to CD8(+) T cells. This heterodimer resides in the membrane of the endoplasmic reticulum, and transports peptides from the cytoplasm into the endoplasmic reticulum lumen for b inding to Mhc class I molecules. The TAP transporter demonstrates spec ificity for both peptide sequence and length, and in rats, allelic var iation in the sequence of the transporter molecules results in differe ntial ability to transport particular peptides. Here we report two exp ressed Sasa-TAP2 loci, both of which are polymorphic, as well as an ex pressed Sasa-TAP1 locus from Atlantic salmon. The Sasa-TAP2A locus has a genomic organization similar to the human TAP2 equivalent.