title: MEKA/phosducin attenuates hydrophobicity of transducin beta gamma subunits without binding to farnesyl moiety.
abstract: Hydrophobic modifications of transducin (T) gamma, such as farnesyl-and carboxyl-methylation, are essential for the association of T beta gamma with the photoreceptor disc membrane, and MEKA/phosducin is known to inhibit the association. In this study, we examined the effect of MEKA on the hydrophobicity of T beta gamma. MEKA could bind to T beta gamma without farnesyl/carboxyl-methyl moieties as well as native T beta gamma. In the Triton X-114 phase separation assay, T beta gamma-MEKA complex was recovered in the aqueous phase, whereas T beta gamma was recover in the detergent phase. N-terminal portion of MEKA which includes T beta gamma-binding domain was not sufficient to reduce the hydrophobicity of T beta gamma or to dissociate T beta gamma from the membrane. The data suggest that MEKA attenuates the hydrophobicity of T beta gamma to result in the dissociation of T beta gamma from the membrane without directly binding to farnesyl/carboxyl-methyl moieties.
authors.affiliation: Department of Pharmacology 1, Osaka University Medical School, Japan. htanaka@pharmal.med.osaka-u.ac.jp
authors.forename: H
authors.initials: H
authors.lastname: Tanaka
authors.forename: C H
authors.initials: CH
authors.lastname: Kuo
authors.forename: T
authors.initials: T
authors.lastname: Matsuda
authors.forename: Y
authors.initials: Y
authors.lastname: Fukada
authors.forename: F
authors.initials: F
authors.lastname: Hayashi
authors.forename: Y
authors.initials: Y
authors.lastname: Ding
authors.forename: Y
authors.initials: Y
authors.lastname: Irie
authors.forename: N
authors.initials: N
authors.lastname: Miki
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D002850:Chromatography, Gel; D005136:Eye Proteins / Q000378:metabolism*; D005204:Farnesol; D020555:GTP-Binding Protein Regulators; D005982:Glutathione Transferase; D016296:Mutagenesis; D010750:Phosphoproteins / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D012160:Retina / Q000378:metabolism; D015293:Transducin / Q000737:chemistry* / Q000378:metabolism
chemical_list: D005136:Eye Proteins; D020555:GTP-Binding Protein Regulators; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; C065631:phosducin; D005204:Farnesol; D005982:Glutathione Transferase; D011494:Protein Kinases; D015293:Transducin