Premium
A structural model for the α‐subunit of transducin Implications of its role as a molecular switch in the visual signal transduction mechanism
Author(s) -
Hingorani Vijay N.,
Ho Yee-Kin
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)80867-0
Subject(s) - transducin , rhodopsin , phosphodiesterase , protein subunit , visual phototransduction , biophysics , g protein , biology , folding (dsp implementation) , gtp' , signal transduction , chemistry , microbiology and biotechnology , biochemistry , enzyme , retinal , engineering , gene , electrical engineering
Transducin is a GTP‐binding protein which mediates the light activation signal from photolyzed rhodopsin to cGMP phosphodiesterase and is pivotal in the visual excitation process. Biochemical studies suggest that the T α subunit of transducin is composed of three functional domains, one for rhodopsin/T βγ interaction, another for guanine nucleotide binding, and a third for the activation of phosphodiesterase. The integration of the primary sequence of T α along with secondary structure, hydropathy and folding topology predictions, and a comparison with homologous proteins have led to the construction of a three‐dimensional model of the T α subunit. A molecular mechanism which underlies the coupling action of T α is suggested on the basis of this model.