title: A novel function of Arp2p in mediating Prk1p-specific regulation of actin and endocytosis in yeast.
abstract: The yeast protein Pan1p plays essential roles in actin cytoskeleton organization and endocytosis. It couples endocytosis with actin polymerization through its dual function in endocytic complex assembly and activation of the actin polymerization initiation complex Arp2/3p. Phosphorylation of Pan1p and other components of the endocytic complex by the kinase Prk1p leads to disassembly of the coat complex and the termination of vesicle-associated actin polymerization. A homologous kinase, Ark1p, has also been implicated in this regulatory process. In this study, we investigated the distinct roles of Prk1p and Ark1p. We found that the nonkinase domains determined the functional specificity of the two kinases. A short region located adjacent to the kinase domain unique to Prk1p was found to be required for the kinase to interact with Arp2p. Further studies demonstrated that the Prk1p-Arp2p interaction is critical for down-regulation of Pan1p. These findings reveal that, in addition to its role in the nucleation of actin polymerization, Arp2p also mediates what appears to be an auto-regulatory mechanism possibly adapted for efficient coordination of actin assembly and disassembly during endocytosis.
authors.affiliation: Institute of Molecular and Cell Biology, Singapore 138673, Republic of Singapore.
authors.forename: Mingji
authors.initials: M
authors.lastname: Jin
authors.forename: Mingjie
authors.initials: M
authors.lastname: Cai
mesh_terms: D051377:Actin-Related Protein 2 / Q000737:chemistry / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D020816:Amino Acid Motifs; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism; D003598:Cytoskeletal Proteins; D004705:Endocytosis; D005656:Fungal Proteins / Q000378:metabolism; D008840:Microfilament Proteins; D009154:Mutation / Q000235:genetics; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: C477632:ARP2 protein, S cerevisiae; D051377:Actin-Related Protein 2; D000199:Actins; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D005656:Fungal Proteins; D008840:Microfilament Proteins; C111870:PAN1 protein, S cerevisiae; C082265:SLA1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C094326:PRK1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases