PSTPIP: a tyrosine phosphorylated cleavage furrow-associated protein that is a substrate for a PEST tyrosine phosphatase.
We have investigated proteins which interact with the PEST-type protein tyrosine phosphatase, PTP hematopoietic stem cell fraction (HSCF), using the yeast two-hybrid system. This resulted in the identification of proline, serine, threonine phosphatase interacting protein (PSTPIP), a novel member of the actin- associated protein family that is homologous to Schizosaccharomyces pombe CDC15p, a phosphorylated protein involved with the assembly of the actin ring in the cytokinetic cleavage furrow. The binding of PTP HSCF to PSTPIP was induced by a novel interaction between the putative coiled-coil region of PSTPIP and the COOH-terminal, proline-rich region of the phosphatase. PSTPIP is tyrosine phosphorylated both endogenously and in v-Src transfected COS cells, and cotransfection of dominant-negative PTP HSCF results in hyperphosphorylation of PSTPIP. This dominant-negative effect is dependent upon the inclusion of the COOH-terminal, proline-rich PSTPIP-binding region of the phosphatase. Confocal microscopy analysis of endogenous PSTPIP revealed colocalization with the cortical actin cytoskeleton, lamellipodia, and actin-rich cytokinetic cleavage furrow. Overexpression of PSTPIP in 3T3 cells resulted in the formation of extended filopodia, consistent with a role for this protein in actin reorganization. Finally, overexpression of mammalian PSTPIP in exponentially growing S. pombe results in a dominant-negative inhibition of cytokinesis. PSTPIP is therefore a novel actin-associated protein, potentially involved with cytokinesis, whose tyrosine phosphorylation is regulated by PTP HSCF.
Spencer
S
S
Department of Molecular Oncology, Genentech, Inc., South San Francisco, California 94080, USA.
Dowbenko
D
D
Cheng
J
J
Li
W
W
Brush
J
J
Utzig
S
S
Simanis
V
V
Lasky
L A
LA
D016475:3T3 Cells; D000199:Actins / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002453:Cell Cycle; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004347:Drug Interactions; D016298:Hematopoietic Cell Growth Factors / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011485:Protein Binding; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12; D017027:Protein Tyrosine Phosphatases / Q000096:biosynthesis / Q000378:metabolism*; D051381:Rats; D012568:Schizosaccharomyces / Q000201:enzymology / Q000254:growth & development; D013347:Subcellular Fractions / Q000378:metabolism; D013379:Substrate Specificity; D014443:Tyrosine / Q000378:metabolism*
D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D016298:Hematopoietic Cell Growth Factors; C110097:Pstpip1 protein, mouse; D014443:Tyrosine; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12; D017027:Protein Tyrosine Phosphatases; C516739:Ptpn12 protein, mouse; C516740:Ptpn12 protein, rat