Three isoforms of synaptic scaffolding molecule and their characterization. Multimerization between the isoforms and their interaction with N-methyl-D-aspartate receptors and SAP90/PSD-95-associated protein.
The synaptic scaffolding molecule (S-SCAM) has been identified as a protein interacting with SAP90/PSD-95-associated protein (SAPAP) (also called guanylate kinase-associated protein/hDLG-associated protein). S-SCAM has six PDZ (we have numbered them PDZ-0 to -5), two WW, and one guanylate kinase (GK) domains and interacts with N-methyl-D-aspartate (NMDA) receptor via PDZ-5 and SAPAP via the GK domain. We have identified here shorter isoforms of S-SCAM that start at the 164th or 224th methionine, and we renamed the original one, S-SCAMalpha, the middle one, S-SCAMbeta, and the shortest one, S-SCAM-gamma. S-SCAMbeta and -gamma have five PDZ (PDZ-1 to -5), two WW, and one GK domains. S-SCAMalpha interacted with S-SCAMbeta and -gamma through the region containing PDZ-4 and -5. The region containing both of PDZ-4 and -5 is sufficient for the clustering of NMDA receptors and forms a dimer in gel filtration, suggesting that S-SCAM forms multimers via the interaction between the C-terminal PDZ domains and assembles NMDA receptors into clusters. S-SCAMbeta and -gamma also interacted with SAPAP, suggesting that the N-terminal region of the GK domain is not necessary for the interaction. Finally, we have identified the interaction of the PDZ domains of S-SCAM with the GK domain of PSD-95/SAP90. S-SCAM, PSD-95/SAP90, and SAPAP are colocalized at least in some part in brain. Therefore, S-SCAM, PSD-95/SAP90, and SAPAP may form a complex in vivo.
Hirao
K
K
Takai Biotimer Project, ERATO, Japan Science and Technology Corporation, JCR Pharmaceuticals Company Limited, 2-2-10 Murotani, Nishi-ku, Kobe 651-2241, Japan.
Hata
Y
Y
Yao
I
I
Deguchi
M
M
Kawabe
H
H
Mizoguchi
A
A
Takai
Y
Y
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001704:Biopolymers; D016466:CHO Cells; D019556:COS Cells; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002531:Cerebellum / Q000378:metabolism; D002850:Chromatography, Gel; D006224:Cricetinae; D017931:DNA Primers; D051528:Guanylate Kinases; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D012160:Retina / Q000378:metabolism; D000074407:SAP90-PSD95 Associated Proteins; D017386:Sequence Homology, Amino Acid
D048868:Adaptor Proteins, Signal Transducing; D001704:Biopolymers; D002352:Carrier Proteins; D017931:DNA Primers; C114103:Magi2 protein, rat; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D016194:Receptors, N-Methyl-D-Aspartate; D000074407:SAP90-PSD95 Associated Proteins; D051528:Guanylate Kinases