CIN85 Is Localized at Synapses and Forms a Complex with S-SCAM via Dendrin

Authors: Kawata, Akira; Iida, Junko; Ikeda, Mitsunobu; Sato, Yuji; Mori, Hiroki; Kansaku, Ai; Sumita, Kazutaka; Fujiwara, Naoyuki; Rokukawa, Chiaki; Hamano, Mamiko; Hirabayashi, Susumu; Hata, Yutaka

Source: The Journal of Biochemistry, Volume 139, Number 5, May 2006 , pp. 931-939(9)

Publisher: Oxford University Press

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Abstract:

Membrane-associated guanylate kinase inverted (MAGI)-1 plays a role as a scaffold at cell junctions in non-neuronal cells, while S-SCAM, its neuronal isoform, is involved in the organization of synapses. A search for MAGI-1-interacting proteins by yeast two-hybrid screening of a kidney cDNA library yielded dendrin. As dendrin was originally reported as a brain-specific postsynaptic protein, we tested the interaction between dendrin and S-SCAM and revealed that dendrin binds to the WW domains of S-SCAM. Dendrin is known to be dendritically translated but its function is largely unknown. To gain insights into the physiological meaning of the interaction, we performed a second yeast two-hybrid screening using dendrin as a bait. We identified CIN85, an endocytic scaffold protein, as a putative dendrin-interactor. Immunocytochemistry and subcellular fractionation analysis supported the synaptic localization of CIN85. The first SH3 domain and the C-terminal region of CIN85 bind to the proline-rich region and the N-terminal region of dendrin, respectively. In vitro experiments suggest that dendrin forms a ternary complex with CIN85 and S-SCAM and that this complex formation facilitates the recruitment of dendrin and S-SCAM to vesicle-like structures where CIN85 is accumulated.

Keywords: dendrites; endocytosis; scaffold; synapses

Document Type: Research article

DOI: http://dx.doi.org/10.1093/jb/mvj105

Publication date: 2006-05-01