Characterization of a multidomain adaptor protein, p140Cap, as part of a pre-synaptic complex.
p140Cap (Cas-associated protein) is an adaptor protein considered to play pivotal roles in cell adhesion, growth and Src tyrosine kinase-related signaling in non-neuronal cells. It is also reported to interact with a pre-synaptic membrane protein, synaptosome-associated protein of 25 kDa, and may participate in neuronal secretion. However, properties and precise functions of p140Cap in neuronal cells are almost unknown. Here we show, using biochemical analyses, that p140Cap is expressed in rat brain in a developmental stage-dependent manner, and is relatively abundant in the synaptic plasma membrane fraction in adults. Immunohistochemistry showed localization of p140Cap in the neuropil in rat brain and immunofluorescent analyses detected p140Cap at synapses of primary cultured rat hippocampal neurons. Electron microscopy further revealed localization at pre- and post-synapses. Screening of p140Cap-binding proteins identified a multidomain adaptor protein, vinexin, whose third Src-homology 3 domain interacts with the C-terminal Pro-rich motif of p140Cap. Immunocomplexes between the two proteins were confirmed in COS7 and rat brain. We also clarified that a pre-synaptic protein, synaptophysin, interacts with p140Cap. These results suggest that p140Cap is involved in neurotransmitter release, synapse formation/maintenance, and signaling.
Ito
Hidenori
H
Department of Molecular Neurobiology, Institute for Developmental Research, Aichi Human Service Center, Kasugai, Japan.
Atsuzawa
Kimie
K
Sudo
Kaori
K
Di Stefano
Paola
P
Iwamoto
Ikuko
I
Morishita
Rika
R
Takei
Shiro
S
Semba
Reiji
R
Defilippi
Paola
P
Asano
Tomiko
T
Usuda
Nobuteru
N
Nagata
Koh-Ichi
K
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D033942:Adaptor Proteins, Vesicular Transport / Q000032:analysis / Q000378:metabolism*; D020816:Amino Acid Motifs / Q000502:physiology; D000818:Animals; D019556:COS Cells; D002454:Cell Differentiation; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D006624:Hippocampus / Q000196:embryology / Q000378:metabolism* / Q000648:ultrastructure; D007150:Immunohistochemistry; D046911:Macromolecular Substances / Q000378:metabolism; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D017729:Presynaptic Terminals / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D015398:Signal Transduction / Q000502:physiology; D013570:Synaptic Membranes / Q000378:metabolism* / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000502:physiology; D016708:Synaptophysin / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D046911:Macromolecular Substances; D008565:Membrane Proteins; C512725:Sorbs3 protein, rat; C000631270:Srcin1 protein, rat; D016708:Synaptophysin