Details

Autor(en) / Beteiligte

• Sun, J
• Zhao, J
• Schwartz, M A
• Wang, J Y
• Wiedmer, T
• Sims, P J

Titel

c-Abl Tyrosine Kinase Binds and Phosphorylates Phospholipid Scramblase 1

Ist Teil von

• The Journal of biological chemistry, 2001-08, Vol.276 (31), p.28984-28990

Ort / Verlag

United States: American Society for Biochemistry and Molecular Biology

Erscheinungsjahr

2001

Quelle

EZB-FREE-00999 freely available EZB journals

Beschreibungen/Notizen

• Phospholipid scramblase 1 (PLSCR1) is a plasma membrane protein that has been proposed to play a role in the transbilayer movement of plasma membrane phospholipids. PLSCR1 contains multiple proline-rich motifs resembling Src homology 3 (SH3) domain-binding sites. An initial screen against 13 different SH3 domains revealed a marked specificity of PLSCR1 for binding to the Abl SH3 domain. Binding between intracellular PLSCR1 and c-Abl was demonstrated by co-immunoprecipitation of both proteins from several cell lines. Deletion of the proline-rich segment in PLSCR1 (residues 1–118) abolished its binding to the Abl SH3 domain. PLSCR1 was Tyr-phosphorylated by c-Abl in vitro . Phosphorylation was abolished by mutation of Tyr residues Tyr 69 /Tyr 74 within the tandem repeat sequence 68 VYNQPVYNQP 77 of PLSCR1, implying that these residues are the likely sites of phosphorylation. Cellular PLSCR1 was found to be constitutively Tyr-phosphorylated in several cell lines. The Tyr phosphorylation of PLSCR1 was increased upon overexpression of c-Abl and significantly reduced either upon cell treatment with the Abl kinase inhibitor STI571, or in Abl−/− mouse fibroblasts, suggesting that cellular PLSCR1 is a normal substrate of c-Abl. Cell treatment with the DNA-damaging agent cisplatin activated c-Abl kinase and increased Tyr phosphorylation of PLSCR1. The cisplatin-induced phosphorylation of PLSCR1 was inhibited by STI571 and was not observed in Abl−/− fibroblasts. These findings indicate that c-Abl binds and phosphorylates PLSCR1, and raise the possibility that an interaction between c-Abl and plasma membrane PLSCR1 might contribute to the cellular response to genotoxic stress.