Delphilin: a novel PDZ and formin homology domain-containing protein that synaptically colocalizes and interacts with glutamate receptor delta 2 subunit.
The glutamate receptor delta2 (GluRdelta2) subunit is selectively expressed in cerebellar Purkinje cells and plays an important role in cerebellar long-term depression, motor learning, motor coordination, and synapse development. We identified a novel GluRdelta2-interacting protein, named Delphilin, that contains a single PDZ domain and formin homology (FH) domains FH1 and FH2 plus coiled-coil structure. As far as we know, this is the first reported protein that contains both PDZ and FH domains. Yeast two-hybrid and surface plasmon resonance (SPR) analyses indicated that Delphilin interacts with the GluRdelta2 C terminus via its PDZ domain. This was also supported by coimmunoprecipitation experiments using a heterologous expression system in mammalian cells. Yeast cell and SPR analyses also demonstrated the possibility that the FH1 proline-rich region of Delphilin interacts with profilin, an actin-binding protein, and with the Src homology 3 domain of neuronal Src protein tyrosine kinase. In situ hybridization demonstrated the highest expression of Delphilin mRNA in Purkinje cells. Delphilin polypeptide was highly enriched in the synaptosomal membrane fraction of the cerebellum and coimmunoprecipitated with the GluRdelta2 subunit. The post-embedding immunogold technique demonstrated that Delphilin is selectively localized at the postsynaptic junction site of the parallel fiber-Purkinje cell synapse and colocalized with GluRdelta2. Thus, Delphilin is a postsynaptic scaffolding protein at the parallel fiber-Purkinje cell synapse, where it may serve to link GluRdelta2 with actin cytoskeleton and various signaling molecules.
Miyagi
Yohei
Y
Departments of Pathology and Bacteriology, Yokohama City University School of Medicine, Yokohama 236-0004, Japan.
Yamashita
Tetsuji
T
Fukaya
Masahiro
M
Sonoda
Tomoko
T
Okuno
Toshiaki
T
Yamada
Kazuyuki
K
Watanabe
Masahiko
M
Nagashima
Yoji
Y
Aoki
Ichiro
I
Okuda
Kenji
K
Mishina
Masayoshi
M
Kawamoto
Susumu
S
D000818:Animals; D001921:Brain / Q000166:cytology / Q000378:metabolism; D002460:Cell Line; D003001:Cloning, Molecular; D003285:Contractile Proteins; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008840:Microfilament Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics*; D051304:Profilins; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D021122:Protein Subunits; D011689:Purkinje Cells / Q000378:metabolism; D017470:Receptors, Glutamate / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D020349:Surface Plasmon Resonance; D013569:Synapses / Q000378:metabolism* / Q000648:ultrastructure; D014162:Transfection; D020798:Two-Hybrid System Techniques; D019061:src-Family Kinases / Q000378:metabolism
D003285:Contractile Proteins; D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; C495738:PFN1 protein, human; C495739:Pfn1 protein, mouse; D051304:Profilins; D021122:Protein Subunits; D017470:Receptors, Glutamate; C447759:delphilin; C107913:glutamate receptor delta 2; D019061:src-Family Kinases