A human TAPBP (TAPASIN)-related gene, TAPBP-R.
TAPASIN, a V-C1 (variable-constant) immunoglobulin superfamily (IgSF) molecule that links MHC class I molecules to the transporter associated with antigen processing (TAP) in the endoplasmic reticulum (ER) is encoded by the TAPBP gene, located near to the MHC at 6p21.3. A related gene was identified at chromosome position 12p13.3 between the CD27 and VAMP1 genes near a group of MHC-paralogous loci. The gene, which we have called TAPBP-R (R for related), also encodes a member of the IgSF, TAPASIN-R. Its putative product contains similar structural motifs to TAPASIN, with some marked differences, especially in the V domain, transmembrane and cytoplasmic regions. By using the mouse ortholog to screen tissue, we revealed that the TAPBP-R gene was broadly expressed. Sub-cellular localization showed that the bulk of TAPASIN-R is located within the ER but biotinylation experiments were consistent with some expression at thecell surface. TAPASIN-R lacks an obvious ER retention signal. The function of TAPASIN-R will be of interest in regards to the evolution of the immune system as well as antigen processing.
Teng
Michelle S
MS
Immunology Division, Department of Pathology, Cambridge, GB.
Stephens
Richard
R
Du Pasquier
Louis
L
Freeman
Tom
T
Lindquist
Jonathan A
JA
Trowsdale
John
J
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002051:Burkitt Lymphoma / Q000473:pathology; D002881:Chromosomes, Human, Pair 12 / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000737:chemistry; D015870:Gene Expression; D015723:Gene Library; D005796:Genes; D006367:HeLa Cells; D006801:Humans; D007136:Immunoglobulins / Q000737:chemistry / Q000235:genetics*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000032:analysis; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D014407:Tumor Cells, Cultured
D018076:DNA, Complementary; D007136:Immunoglobulins; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; C454688:TAPBPL protein, human