|PROSITE documentation PDOC00574|
β-transducin (G-β) is one of the three subunits (α, β, and γ) of the guanine nucleotide-binding proteins (G proteins) which act as intermediaries in the transduction of signals generated by transmembrane receptors . The α subunit binds to and hydrolyzes GTP; the functions of the β and γ subunits are less clear but they seem to be required for the replacement of GDP by GTP as well as for membrane anchoring and receptor recognition.
In higher eukaryotes G-β exists as a small multigene family of highly conserved proteins of about 340 amino acid residues. Structurally G-β consists of eight tandem repeats of about 40 residues, each containing a central Trp-Asp motif (this type of repeat is sometimes called a WD-40 repeat). Such a repetitive segment has been shown [2,3,4,5] to exist in a number of other proteins listed below:
The number of repeats in the above proteins varies between 5 (PRP4, TUP1, and Groucho) and 8 (G-β, STE4, MSI1, AAC3, CDC4, PWP1, etc.). In G-β and G-β like proteins, the repeats span the entire length of the sequence, while in other proteins, they make up the N-terminal, the central or the C-terminal section.
A signature pattern can be developed from the central core of the domain (positions 9 to 23).
Two profiles were developed for this module, the first one picks up WD repeats while the second profile is 'circular' and will thus detect a region containing adjacent WD repeats.Last update:
December 2004 / Pattern and text revised.
PROSITE methods (with tools and information) covered by this documentation:
|Title||G proteins: transducers of receptor-generated signals.|
|Source||Annu. Rev. Biochem. 56:615-649(1987).|
|2||Authors||Duronio R.J. Gordon J.I. Boguski M.S.|
|Title||Comparative analysis of the beta transducin family with identification of several new members including PWP1, a nonessential gene of Saccharomyces cerevisiae that is divergently transcribed from NMT1.|
|3||Authors||van der Voorn L. Ploegh H.L.|
|Source||FEBS Lett. 307:131-134(1992).|
|4||Authors||Neer E.J. Schmidt C.J. Nambudripad R. Smith T.F.|
|Title||The ancient regulatory-protein family of WD-repeat proteins.|
|5||Authors||Smith T.F. Gaitatzes C. Saxena K. Neer E.J.|
|Title||The WD repeat: a common architecture for diverse functions.|
|Source||Trends Biochem. Sci. 24:181-185(1999).|