Alternate forms of MHC class II-associated invariant chain are not produced by alternative splicing in rainbow trout (Oncorhynchus mykiss) but are encoded by separate genes.
A major limiting factor in understanding teleost major histocompatibility receptor function is the lack of knowledge about antigen presentation accessory molecules. We report here two cDNA clones encoding teleost versions of invariant chain and one encoding a related protein that may play a protease inhibition role in antigen presentation. The two invariant chain equivalents are similar to each other where they overlap, but differ in the presence or absence of a thyroglobulin domain. This domain is added to tetrapod invariant chain protein by alternative splicing but there was no evidence of alternative splicing of the two trout genes. Southern blotting confirmed that all three trout cDNAs are derived from single copy genes and Northern blotting indicated that they are expressed in antigen tissues. Thus the encoded proteins are probably involved in antigen presentation, but their expression is probably regulated in a manner different from tetrapods.
Fujiki
Kazuhiro
K
Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ont, Canada N2L 3G1.
Smith
Cortney M
CM
Liu
Lei
L
Sundick
Roy S
RS
Dixon
Brian
B
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D000944:Antigens, Differentiation, B-Lymphocyte / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002999:Clone Cells; D018628:Gene Dosage; D005796:Genes; D005802:Genes, MHC Class II; D000949:Histocompatibility Antigens Class II / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D017686:Oncorhynchus mykiss / Q000235:genetics* / Q000276:immunology; D016415:Sequence Alignment
D000944:Antigens, Differentiation, B-Lymphocyte; D000949:Histocompatibility Antigens Class II; C045084:invariant chain