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Regulation of the p21-activated kinase (PAK) by a human Gbeta -like WD-repeat protein, hPIP1.

The family of p21-activated protein kinases (PAKs) is composed of serine-threonine kinases whose activity is regulated by the small guanosine triphosphatases (GTPases) Rac and Cdc42. In mammalian cells, PAKs have been implicated in the regulation of mitogen-activated protein cascades, cellular morphological and cytoskeletal changes, neurite outgrowth, and cell apoptosis. Although the ability of Cdc42 and Rac GTPases to activate PAK is well established, relatively little is known about the negative regulation of PAK or the identity of PAK cellular targets. Here, we describe the identification and characterization of a human PAK-interacting protein, hPIP1. hPIP1 contains G protein beta-like WD repeats and shares sequence homology with the essential fission yeast PAK regulator, Skb15, as well as the essential budding yeast protein, MAK11. Interaction of hPIP1 with PAK1 inhibits the Cdc42/Rac-stimulated kinase activity through the N-terminal regulatory domains of PAK1. Cotransfection of hPIP1 in mammalian cells inhibits PAK-mediated c-Jun N-terminal kinase and nuclear factor kappa B signaling pathways. Our results demonstrate that hPIP1 is a negative regulator of PAK and PAK signaling pathways.

Pubmed ID: 11371639


  • Xia C
  • Ma W
  • Stafford LJ
  • Marcus S
  • Xiong WC
  • Liu M


Proceedings of the National Academy of Sciences of the United States of America

Publication Data

May 22, 2001

Associated Grants

  • Agency: NIGMS NIH HHS, Id: R0I GM53239

Mesh Terms

  • Amino Acid Sequence
  • Animals
  • COS Cells
  • Carrier Proteins
  • Cell Size
  • Cercopithecus aethiops
  • Cloning, Molecular
  • Cytoskeleton
  • GTP-Binding Proteins
  • Gene Expression
  • Humans
  • Intracellular Signaling Peptides and Proteins
  • Isoenzymes
  • JNK Mitogen-Activated Protein Kinases
  • Mice
  • Mitogen-Activated Protein Kinases
  • Molecular Sequence Data
  • NF-kappa B
  • Phospholipase C beta
  • Protein-Serine-Threonine Kinases
  • Recombinant Fusion Proteins
  • Tissue Distribution
  • Type C Phospholipases
  • cdc42 GTP-Binding Protein
  • p21-Activated Kinases