Cloning and characterization of a novel Cdc42-associated tyrosine kinase, ACK-2, from bovine brain.
Cdc42 plays an important role in intracellular signaling pathways that influence cell morphology and motility and stimulate DNA synthesis. In attempts to determine whether nonreceptor tyrosine kinases play a fundamental role in Cdc42 signaling, we have cloned and biochemically characterized a new Cdc42-associated tyrosine kinase (ACK) from bovine brain. This tyrosine kinase, named ACK-2, has a calculated molecular mass of 83 kDa and shares a number of primary structural domains with the 120-kDa ACK (ACK-1). The main differences between the primary structures of ACK-2 and ACK-1 occur in the amino- and carboxyl-terminal regions. Like ACK-1, ACK-2 binds exclusively to activated (GTP-bound) Cdc42 and does not bind to its closest homologs, e.g. activated Rac. ACK-2 could not be activated by addition of glutathione S-transferase (GST)-Cdc42(Q61L), a GTPase-defective mutant, or by GTPgammaS-loaded GST-Cdc42 in in vitro kinase assays. However, ACK-2 was activated when cotransfected with wild type Cdc42 or Cdc42(Q61L) and stably associated with Cdc42(Q61L) in vivo, indicating that ACK-2 interacts with active Cdc42 in cells. Furthermore, the tyrosine kinase activity of ACK-2 was stimulated both by epidermal growth factor and bradykinin, suggesting that ACK-2 may play a role in the signaling actions of both receptor tyrosine kinases or heterotrimeric G-protein-coupled receptors.
Yang
W
W
Department of Pharmacology, Cornell University, Ithaca, New York 14853-6401, USA.
Cerione
R A
RA
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001920:Bradykinin / Q000494:pharmacology; D001921:Brain / Q000201:enzymology*; D019556:COS Cells; D002417:Cattle; D002448:Cell Adhesion; D018797:Cell Cycle Proteins / Q000378:metabolism*; D003001:Cloning, Molecular; D017931:DNA Primers; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011487:Protein Conformation; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae
D018797:Cell Cycle Proteins; D017931:DNA Primers; D011994:Recombinant Proteins; D004815:Epidermal Growth Factor; D011505:Protein-Tyrosine Kinases; D019204:GTP-Binding Proteins; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae; D001920:Bradykinin