The endocytic protein intersectin is a major binding partner for the Ras exchange factor mSos1 in rat brain.
We recently identified intersectin, a protein containing two EH and five SH3 domains, as a component of the endocytic machinery. The N-terminal SH3 domain (SH3A), unlike other SH3 domains from intersectin or various endocytic proteins, specifically inhibits intermediate events leading to the formation of clathrin-coated pits. We have now identified a brain-enriched, 170 kDa protein (p170) that interacts specifically with SH3A. Screening of combinatorial peptides reveals the optimal ligand for SH3A as Pp(V/I)PPR, and the 170 kDa mammalian son-of-sevenless (mSos1) protein, a guanine-nucleotide exchange factor for Ras, con- tains two copies of the matching sequence, PPVPPR. Immunodepletion studies confirm that p170 is mSos1. Intersectin and mSos1 are co-enriched in nerve terminals and are co-immunoprecipitated from brain extracts. SH3A competes with the SH3 domains of Grb2 in binding to mSos1, and the intersectin-mSos1 complex can be separated from Grb2 by sucrose gradient centrifugation. Overexpression of the SH3 domains of intersectin blocks epidermal growth factor-mediated Ras activation. These results suggest that intersectin functions in cell signaling in addition to its role in endocytosis and may link these cellular processes.
Tong
X K
XK
Department of Neurology, Montreal Neurological Institute, Montreal, QC H3A 2B4, Canada.
Hussain
N K
NK
de Heuvel
E
E
Kurakin
A
A
Abi-Jaoude
E
E
Quinn
C C
CC
Olson
M F
MF
Marais
R
R
Baranes
D
D
Kay
B K
BK
McPherson
P S
PS
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D016384:Consensus Sequence; D011992:Endosomes / Q000737:chemistry*; D004789:Enzyme Activation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000037:antagonists & inhibitors / Q000494:pharmacology; D051380:GRB2 Adaptor Protein; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009474:Neurons / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D011485:Protein Binding; D011506:Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000737:chemistry / Q000378:metabolism; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D020837:SOS1 Protein / Q000737:chemistry / Q000378:metabolism*; D020663:ras Guanine Nucleotide Exchange Factors / Q000737:chemistry / Q000378:metabolism*; D018909:src Homology Domains / Q000235:genetics / Q000502:physiology
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D002352:Carrier Proteins; D051380:GRB2 Adaptor Protein; C495950:Grb2 protein, rat; D011506:Proteins; D011993:Recombinant Fusion Proteins; D020837:SOS1 Protein; C115919:intersectin 1; D020663:ras Guanine Nucleotide Exchange Factors; D004815:Epidermal Growth Factor; D016283:Proto-Oncogene Proteins p21(ras)