Characterization of the molecular chaperone calnexin in the channel catfish, Ictalurus punctatus, and its association with MHC class II molecules

• Published in: Developmental & Comparative Immunology 2004-05, Vol.28 (6), p.603-617
• Main Authors: Fuller, James R, Pitzer, Joshua E, Godwin, Ulla, Albertino, Mark, Machon, Benjamin D, Kearse, Kelly P, McConnell, Thomas J
• Format: Article
• Language: English
• Subjects: Amino Acid Motifs; Amino Acid Sequence; Animals; Base Sequence; Calnexin; Calnexin - chemistry; Calnexin - genetics; Calnexin - immunology; Calnexin - metabolism; Channel catfish; Chaperone; chaperones; Class II; Comparative immunology; Electrophoresis, Polyacrylamide Gel - veterinary; Female; Freshwater; Histocompatibility Antigens Class II - immunology; Histocompatibility Antigens Class II - metabolism; Ictaluridae - genetics; Ictaluridae - immunology; Ictaluridae - metabolism; Ictalurus punctatus; Major histocompatibility complex; Mice; Mice, Inbred BALB C; Molecular Chaperones - genetics; Molecular Chaperones - immunology; Molecular Chaperones - metabolism; Molecular Sequence Data; Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase - metabolism; Phylogeny; Precipitin Tests - veterinary; Recombinant Proteins; Reverse Transcriptase Polymerase Chain Reaction - veterinary; RNA - chemistry; RNA - genetics; Sequence Alignment; Teleost; Teleostei
• ISSN: 0145-305X; 1879-0089; 1365-2567
• DOI: 10.1016/j.dci.2003.11.002

Folding and assembly of MHC molecules in mammals occurs in the endoplasmic reticulum (ER), but has not been studied in teleosts. Calnexin (CNX) is an ER chaperone that associates with glycoproteins bearing a monoglucosylated N-linked oligosaccharide side chain. Here we report the first identification and characterization of a full-length CNX cDNA clone in a teleost, and the association of the CNX chaperone with MHC class II in a channel catfish T cell line. The 1.8 kb CNX clone encodes a protein of 607 amino acids that is 72% identical to the consensus sequence of mammalian CNXs. The association of CNX with class II is of particular interest because the native MHC class II α chain of Ictalurus punctatus does not bear any N-linked oligosaccharide consensus glycosylation sequences. Thus the assembly of class II molecules in the catfish probably proceeds via different steps than occurs in mammals.