Structural and functional differences of two forms of GTP-binding protein, Gq, in the cephalopod retina.
Comp Biochem Physiol B Biochem Mol Biol
; 123(3): 319-27, 1999 Jul.
Article
em En
| MEDLINE
| ID: mdl-10481260
ABSTRACT
The major GTP-binding protein (G-protein) in the rhabdomeric photoreceptor membranes of the squid (Watasenia scintillans) has been identified as a Gq-class G-protein. Anti-Gq alpha antibodies recognized a protein not only in the photoreceptor membranes but also in soluble fractions of the retina. The 42 kD protein in the soluble fractions (soluble Gq alpha) had the same molecular mass and the same reactivities to anti-Gq antibodies as those of membrane-bound Gq alpha. The G beta subunit was scarcely detected in the soluble fractions, being found mostly in the membrane fraction, indicating soluble Gq alpha exists in monomeric form. Soluble Gq alpha had no effect on the GTPase activity of the photoreceptor membranes, suggesting that it does not interact with photoactivated rhodopsin or G beta gamma. Soluble Gq alpha would be an inactive form of Gq alpha. In the retina of Octopus fangsiao, soluble Gq alpha was scarcely detected after dark adaptation, but increased during subsequent light exposure and decreased on returning to dark adaptation. These results with Octopus suggest that functional membrane-bound Gq alpha is converted to soluble Gq alpha on exposure to light. Transformation of membrane-bound Gq alpha into the soluble form by hydroxylamine suggests that the difference between membrane-bound and soluble Gq alpha is associated with the attachment of fatty acid(s).
Buscar no Google
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Células Fotorreceptoras de Invertebrados
/
Proteínas de Ligação ao GTP
Limite:
Animals
Idioma:
En
Revista:
Comp Biochem Physiol B Biochem Mol Biol
Assunto da revista:
BIOLOGIA MOLECULAR
/
BIOQUIMICA
Ano de publicação:
1999
Tipo de documento:
Article
País de afiliação:
Japão