Differential expression of Q4 proteins (Qb-1) in fibroblasts and lymphocytes.
The Qb-1 protein is coded for by the Q4 gene. This gene appears to be widely transcribed in murine tissues. We have examined the subcellular localization and processing of Qb-1 in fibroblast cells. This protein has previously been reported to be secreted from activated lymphocytes. However, we report that high levels of Qb-1 are present on the surface of B10.P fibroblast cells. We also observed an unusual intracellular distribution for Qb-1. The protein appears to be highly concentrated in the endoplasmic reticulum, in addition to being on the surface. This distribution is not due to inefficient processing. The kinetics of Qb-1 processing and transport are not unusual for class I molecules. Complete resistance to endo-beta-N-acetylglucosaminidase H is acquired, indicating terminal processing. This unusual localization in fibroblast cells and the differential expression of this protein between cell types may reflect a specific role for Qb-1.
Department of Microbiology and Immunology, University of North Carolina, Chapel Hill 27599.
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Frelinger
D000595:Amino Acid Sequence; D002451:Cell Compartmentation; D002462:Cell Membrane / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism*; D015870:Gene Expression; D006183:H-2 Antigens / Q000737:chemistry / Q000378:metabolism; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000378:metabolism*; D007158:Immunologic Techniques; D008214:Lymphocytes / Q000378:metabolism*; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D016415:Sequence Alignment
D006183:H-2 Antigens; D015395:Histocompatibility Antigens Class I; D009841:Oligonucleotides; D010455:Peptides; C032907:Q surface antigens