Homologous Superfamily

Phosducin, N-terminal domain superfamily (IPR023196)

Short name: Phosducin_N_dom_sf

Overlapping entries


The outer and inner segments of vertebrate rod photoreceptor cells contain phosducin, a soluble phosphoprotein that complexes with the beta/gamma-subunits of the GTP-binding protein, transducin. Light-induced changes in cyclic nucleotide levels modulate the phosphorylation of phosducin by protein kinase A [PMID: 2203790]. The protein is thought to participate in the regulation of visual phototransduction or in the integration of photo-receptor metabolism. Similar proteins have been isolated from the pineal gland and it is believed that the functional role of the protein is the same in both retina and pineal gland [PMID: 2210381].

This superfamily represents the N-terminal domain of phosducin. Together with the C-terminal domain, it covers one side and the top of the seven-bladed beta propeller of Gt beta gamma. The binding of phosducin induces a distinct structural change in the beta propeller of Gt beta gamma, such that a small cavity opens up between blades 6 and 7 [PMID: 9739091]. Binding of phosducin results in sequestration of beta gamma from the membrane to the cytosol and turns off the signal-transduction cascade. Regulation of this membrane association/dissociation switch of Gt beta gamma by phosducin may be a general mechanism for attenuation of G protein coupled signal transduction cascades.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.