Recombinant Human Girdin (CCDC88A), partial

Function

Bifunctional modulator of guanine nucleotide-binding proteins (G proteins) (PubMed:19211784, PubMed:27621449). Acts as a non-receptor guanine nucleotide exchange factor which binds to and activates guanine nucleotide-binding protein G(i) alpha subunits (PubMed:19211784, PubMed:21954290, PubMed:23509302, PubMed:25187647). Also acts as a guanine nucleotide dissociation inhibitor for guanine nucleotide-binding protein G(s) subunit alpha GNAS (PubMed:27621449). Essential for cell migration (PubMed:16139227, PubMed:19211784, PubMed:20462955, PubMed:21954290). Interacts in complex with G(i) alpha subunits with the EGFR receptor, retaining EGFR at the cell membrane following ligand stimulation and promoting EGFR signaling which triggers cell migration (PubMed:20462955). Binding to Gi-alpha subunits displaces the beta and gamma subunits from the heterotrimeric G protein complex which enhances phosphoinositide 3-kinase (PI3K)-dependent phosphorylation and kinase activity of AKT1/PKB (PubMed:19211784). Phosphorylation of AKT1/PKB induces the phosphorylation of downstream effectors GSK3 and FOXO1/FKHR, and regulates DNA replication and cell proliferation (By similarity). Binds in its tyrosine-phosphorylated form to the phosphatidylinositol 3-kinase (PI3K) regulatory subunit PIK3R1 which enables recruitment of PIK3R1 to the EGFR receptor, enhancing PI3K activity and cell migration (PubMed:21954290). Plays a role as a key modulator of the AKT-mTOR signaling pathway, controlling the tempo of the process of newborn neuron integration during adult neurogenesis, including correct neuron positioning, dendritic development and synapse formation (By similarity). Inhibition of G(s) subunit alpha GNAS leads to reduced cellular levels of cAMP and suppression of cell proliferation (PubMed:27621449). Essential for the integrity of the actin cytoskeleton (PubMed:16139227, PubMed:19211784). Required for formation of actin stress fibers and lamellipodia (PubMed:15882442). May be involved in membrane sorting in the early endosome (PubMed:15882442). Plays a role in ciliogenesis and cilium morphology and positioning and this may partly be through regulation of the localization of scaffolding protein CROCC/Rootletin (PubMed:27623382)

Subcellular Location

Cell membrane (Peripheral membrane protein); Cytoplasm, cytosol; Cytoplasmic vesicle; Cell projection, lamellipodium; Cytoplasm, cytoskeleton, cilium basal body; Cytoplasm, cytoskeleton, microtubule organizing center, centrosome, centriole

Disease Association

PEHO-like syndrome (PEHOL) : An autosomal recessive syndrome characterized by microcephaly and moderately severe hypotonia manifesting at birth, seizures that progress into infantile spasms with hypsarrhythmia, brain atrophy with bilateral polymicrogyria and pachygyria, thin corpus callosum, and mild reduction in cerebellar vermis volume. Patients also display optic atrophy, severe cognitive delay, puffiness of the maxillary region of the face, and edema of the dorsum of the hands and feet. [The disease is caused by variants affecting the gene represented in this entry]

Tissue Specificity

Expressed ubiquitously

Subunit

Homodimer (PubMed:16139227). Interacts (via GBA motif) with guanine nucleotide-binding protein G(i) alpha subunits GNAI1, GNAI2 and GNAI3 (PubMed:19211784, PubMed:21954290, PubMed:23509302, PubMed:27621449, PubMed:31363053). Also interacts (via GNA motif) with guanine nucleotide-binding protein G(s) alpha subunit GNAS (PubMed:27621449). Interaction with G(i) alpha subunits occurs before interaction with GNAS and is regulated by phosphorylation; phosphorylation at Ser-1675 enhances binding to G(i) alpha subunits while phosphorylation at Ser-1690 abolishes G(i) alpha subunit binding, promoting binding to GNAS (PubMed:27621449). Interacts (via C-terminal SH2-like region) with growth factor receptors EGFR, INSR and KDR/VEGFR2 (via their autophosphorylated cytoplasmic tails) (PubMed:25187647). Forms a complex with EGFR and GNAI3 which leads to enhanced EGFR signaling and triggering of cell migration; ligand stimulation is required for recruitment of GNAI3 to the complex (PubMed:20462955, PubMed:25187647). Interacts (tyrosine-phosphorylated form) with phosphatidylinositol 3-kinase (PI3K) regulatory subunit PIK3R1/p85a (via SH2 domains); the interaction enables recruitment of PIK3R1 to the EGFR receptor, enhancing PI3K activity and cell migration (PubMed:21954290). Interacts with serine/threonine-protein kinase PRKCQ; the interaction leads to phosphorylation of CCDC88A and inhibition of its guanine nucleotide exchange factor activity (PubMed:23509302). Interacts (via C-terminus) with DISC1; the interaction is direct (By similarity). Interacts with AKT proteins; the interaction is inhibited in the presence of DISC1 (By similarity). Interacts with AKT1/PKB (via C-terminus) (PubMed:16139227). The non-phosphorylated form interacts with phosphatidylinositol 4-phosphate [PI(4)P] and weakly with phosphatidylinositol 3-phosphate [PI(3)P] (PubMed:16139227). Interacts with microtubules (By similarity). Interacts with actin (PubMed:16139227)

• Enomoto A. et al. Akt/PKB regulates actin organization and cell motility via Girdin/APE. — Dev. Cell (2005)
• Simpson F. et al. A novel hook-related protein family and the characterization of hook-related protein 1. — Traffic (2005)
• Anai M. et al. PubMed: CI-1UI656D1JB9JK (NOV-)
• Hillier L.W. et al. Generation and annotation of the DNA sequences of human chromosomes 2 and 4. — Nature (2005)
• The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). — Genome Res. (2004)
• Bechtel S. et al. The full-ORF clone resource of the German cDNA consortium. — BMC Genomics (2007)
• Le-Niculescu H. et al. Identification and characterization of GIV, a novel Galpha i/s-interacting protein found on COPI, endoplasmic reticulum-Golgi transport vesicles. — J. Biol. Chem. (2005)
• Enomoto A. et al. Girdin, a novel actin-binding protein, and its family of proteins possess versatile functions in the Akt and Wnt signaling pathways. — Ann. N. Y. Acad. Sci. (2006)