title: SNX9 as an adaptor for linking synaptojanin-1 to the Cdc42 effector ACK1.
abstract: Sorting nexin 9 (SNX9, also referred to as SH3PX1) is a binding partner for the non-receptor and Cdc42-associated kinase (ACK) in Drosophila and mammals. ACK1 is known to bind clathrin and influence EGF receptor endocytosis. SNX9 comprises an N-terminal Src homology domain 3 (SH3), a central PHOX homology (PX) domain, and a carboxyl-terminal coiled-coil region. In order to investigate SNX9 further we have made use of a novel in vivo biotinylation system to label various GST-SH3 domains and perform blot overlays, thereby identifying synaptojanin-1 as a partner for SNX9. Biotinylated SH3 domains were also used for specific identification of target proline-rich sequences in synaptojanin and ACK1 on synthetic peptides arrays. Direct assessment of SH3 binding efficiencies at different positions within the extensive proline-rich regions of these proteins were thus determined. While SNX9 targets a number of sequences within the proline-rich regions of synaptojanin, a single site was identified in human ACK1. By testing the association of various truncations of ACK1 with SNX9 we confirmed the dominant SNX9 binding domain in human ACK1 (residues 920-955). In the presence of SNX9 we find that synaptojanin is able to colocalize with distinct ACK1 containing vesicles, indicating that this tyrosine kinase is linked to many components involved in vesicle dynamics including clathrin, AP2 and synaptojanin-1.
authors.affiliation: GSK-IMCB Laboratory, Institute of Molecular and Cell Biology, Proteos Building, 61 Biopolis Drive, Singapore 138673, Singapore.
authors.forename: Lee
authors.initials: L
authors.lastname: Yeow-Fong
authors.forename: Louis
authors.initials: L
authors.lastname: Lim
authors.forename: Ed
authors.initials: E
authors.lastname: Manser
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D058305:Sorting Nexins; D033921:Vesicular Transport Proteins; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*; D018909:src Homology Domains
chemical_list: D002352:Carrier Proteins; D029721:Drosophila Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D011993:Recombinant Fusion Proteins; C498519:SH3PX1 protein, Drosophila; C400533:SNX9 protein, human; D058305:Sorting Nexins; D033921:Vesicular Transport Proteins; C498593:Ack protein, Drosophila; D011505:Protein-Tyrosine Kinases; C403262:TNK2 protein, human; C097702:synaptojanin; D010744:Phosphoric Monoester Hydrolases; D020764:cdc42 GTP-Binding Protein