Identification of the Sites of Interaction between Lymphocyte Phosphatase-associated Phosphoprotein (LPAP) and CD45 (∗)

• Published in: The Journal of biological chemistry Vol. 270; no. 52; pp. 31372 - 31376
• Main Authors: Bruyns, Eddy, Hendricks-Taylor, L. Ranee, Meuer, Stefan, Koretzky, Gary A., Schraven, Burkhart
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 29.12.1995; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Sequence; Base Sequence; Cell Membrane - metabolism; Cloning, Molecular; DNA, Complementary; Humans; Intracellular Signaling Peptides and Proteins; Leukocyte Common Antigens - metabolism; Membrane Proteins; Molecular Sequence Data; Mutagenesis, Site-Directed; Oligodeoxyribonucleotides; Phosphoproteins - genetics; Phosphoproteins - metabolism; Protein Binding
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.270.52.31372

Human lymphocyte phosphatase-associated phosphoprotein (LPAP) is a phosphoprotein of unknown function that noncovalently associates with CD45 in lymphocytes. In CD45-deficient human T cells, LPAP protein is synthesized at normal levels but is more rapidly degraded than in wild-type cells. Expression of CD45 cDNA rescues LPAP protein expression. This strongly suggests that LPAP is protected from degradation through its interaction with CD45. We have mapped the sites of interaction between LPAP and CD45 employing chimeric CD45 molecules and LPAP deletion mutants. Our data demonstrate that the interaction between LPAP and CD45 is mediated via the transmembrane regions of both molecules. In addition, the intracytoplasmic amino acids adjacent to the transmembrane region of LPAP may influence its binding to CD45.