Guanine nucleotide-binding protein G(i) subunit alpha-3
Function
Heterotrimeric guanine nucleotide-binding proteins (G proteins) function as transducers downstream of G protein-coupled receptors (GPCRs) in numerous signaling cascades. The alpha chain contains the guanine nucleotide binding site and alternates between an active, GTP-bound state and an inactive, GDP-bound state. Signaling by an activated GPCR promotes GDP release and GTP binding. The alpha subunit has a low GTPase activity that converts bound GTP to GDP, thereby terminating the signal. Both GDP release and GTP hydrolysis are modulated by numerous regulatory proteins (PubMed:18434541, PubMed:19478087, PubMed:8774883). Signaling is mediated via effector proteins, such as adenylate cyclase. Inhibits adenylate cyclase activity, leading to decreased intracellular cAMP levels (PubMed:19478087). Stimulates the activity of receptor-regulated K(+) channels (PubMed:2535845). The active GTP-bound form prevents the association of RGS14 with centrosomes and is required for the translocation of RGS14 from the cytoplasm to the plasma membrane. May play a role in cell division (PubMed:17635935).
Involvement in disease
Auriculocondylar syndrome 1
ARCND1
An autosomal dominant form of auriculocondylar syndrome, a craniofacial malformation syndrome characterized by variable mandibular anomalies, including mild to severe micrognathia, temporomandibular joint ankylosis, cleft palate, and a characteristic ear malformation that consists of separation of the lobule from the external ear, giving the appearance of a question mark (question-mark ear). Other frequently described features include prominent cheeks, cupped and posteriorly rotated ears, preauricular tags, and microstomia. Glossoptosis, masticatory abnormalities, orthodontic problems, and malocclusion occur in a majority of affected subjects.
None
The disease is caused by variants affecting the gene represented in this entry.
Post-translational modifications
(Microbial infection) Deamidated at Gln-204 by Photorhabdus asymbiotica toxin PAU_02230, blocking GTP hydrolysis of heterotrimeric GNAQ or GNA11 and G-alphai (GNAI1, GNAI2 or GNAI3) proteins, thereby activating RhoA.
Sequence Similarities
Belongs to the G-alpha family. G(i/o/t/z) subfamily.
Cellular localization
- Cytoplasm
- Cell membrane
- Lipid-anchor
- Cytoplasm
- Cytoskeleton
- Microtubule organizing center
- Centrosome
- Localizes in the centrosomes of interphase and mitotic cells. Detected at the cleavage furrow and/or the midbody.
Alternative names
Guanine nucleotide-binding protein G(i) subunit alpha-3, G(i) alpha-3, GNAI3