title: CD45-associated protein is a lymphocyte-specific membrane protein expressed in two distinct forms.
abstract: CD45-AP is a recently identified CD45-associated protein. The two proteins interact specifically through their respective transmembrane segments. Northern hybridization analysis of CD45+ T lymphocytes and their CD45- variants demonstrated that the production of CD45-AP and CD45 mRNA is regulated independently. On the other hand, Western blotting analysis indicated that the CD45-AP protein has a shorter half-life in the absence of CD45 in three out of four variants. Similar analysis of various types of leukocytes demonstrated that CD45-AP is expressed in T, B, and pre-B cells, but not in plasma cells or cells of the monocyte/macrophage lineage. Two forms of CD45-AP mRNA exist in all types of CD45-AP-expressing lymphocytes analyzed. One form corresponds to the previously reported CD45-AP cDNA and the other form encodes an additional 12 amino acids at the N terminus. The two CD45-AP proteins are identical in their capacity for specific binding to CD45, but employ different mechanisms for endoplasmic reticulum membrane translocation.
authors.affiliation: Department of Pathology, Roger Williams Medical Center-Brown University, Providence, RI 02908, USA.
authors.forename: K
authors.initials: K
authors.lastname: Kitamura
authors.forename: A
authors.initials: A
authors.lastname: Matsuda
authors.forename: S
authors.initials: S
authors.lastname: Motoya
authors.forename: A
authors.initials: A
authors.lastname: Takeda
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D015723:Gene Library; D047908:Intracellular Signaling Peptides and Proteins; D017493:Leukocyte Common Antigens / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008565:Membrane Proteins / Q000032:analysis* / Q000096:biosynthesis*; D051379:Mice; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000032:analysis* / Q000096:biosynthesis* / Q000378:metabolism; D011485:Protein Binding / Q000276:immunology; D014176:Protein Biosynthesis / Q000276:immunology; D012333:RNA, Messenger / Q000096:biosynthesis; D013601:T-Lymphocytes / Q000378:metabolism*; D014158:Transcription, Genetic / Q000276:immunology
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D010750:Phosphoproteins; C513303:Ptprcap protein, mouse; D012333:RNA, Messenger; D017493:Leukocyte Common Antigens