B cell receptor accessory molecules in the channel catfish, Ictalurus punctatus.
B cell receptor (BCR) accessory molecules CD79a and CD79b homologs were identified in the channel catfish, Ictalurus punctatus. Both are found as single copy genes that encode proteins containing a signal peptide, an extracellular immunoglobulin domain, a transmembrane region and a cytoplasmic tail containing an immune-receptor tyrosine-dased activation motif (ITAM). IpCD79a and IpCD79b transcripts correlate well with IgM message expression. They are highly expressed in peripheral blood leukocytes (PBL) enriched in membrane (m) IgM+ cells and catfish clonal B cell lines, but not in catfish clonal T cells, indicating that IpCD79a and IpCD79b expression is B cell restricted. Studies using catfish clonal B cells (3B11) transfected with constructs encoding epitope-tagged IpCD79a and IpCD79b revealed that IpCD79a was expressed as a 45 kDa protein and IpCD79b was expressed as a 32 kDa protein. Furthermore, co-immunoprecipitations of epitope-tagged CD79 proteins demonstrate that these molecules are non-covalently associated with mIgM. These data correlate with some of the previous immunoprecipitation data demonstrating that catfish mIgM associates with proteins of 45 and 32 kDa.
Department of Microbiology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216-4505, USA.
Manoranjan
M
Sahoo
Eva-Stina
ES
Edholm
James L
JL
Stafford
Eva
E
Bengtén
Norman W
NW
Miller
Melanie
M
Wilson
D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology; D001483:Base Sequence; D051925:CD79 Antigens / Q000737:chemistry / Q000235:genetics* / Q000276:immunology / Q000378:metabolism*; D002397:Catfishes / Q000235:genetics* / Q000276:immunology / Q000378:metabolism*; D002460:Cell Line; D005786:Gene Expression Regulation; D007075:Immunoglobulin M / Q000276:immunology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010802:Phylogeny; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D051925:CD79 Antigens; D007075:Immunoglobulin M