Assuntos
Núcleo Celular/metabolismo , DNA/metabolismo , Receptores de Glucocorticoides/metabolismo , Receptores de Esteroides/metabolismo , Animais , Citosol/metabolismo , Dexametasona/metabolismo , Variação Genética , Cinética , Linfoma/metabolismo , Camundongos , Neoplasias Experimentais/metabolismo , Receptores de Glucocorticoides/genética , Receptores de Glucocorticoides/isolamento & purificaçãoRESUMO
[3H]Triamcinolone acetonide was used to tag covalently specific glucocorticoid receptors by photoaffinity labelling at lambda greater than or equal to 320 nm. Receptors of wild-type mouse lymphoma cells and two glucocorticoid resistant mutants of "nuclear transfer deficient" (nt-) and "increased nuclear transfer" (nti) phenotypes, respectively, were used. Wild-type and nt- receptors yielded radiolabelled polypeptide bands of mol. wt. 98 000 as revealed by gel electrophoresis under denaturing conditions and fluorography. In contrast, the nti receptor had a mol. wt. of 42 000. Partial proteolysis of the wild-type receptor with alpha-chymotrypsin resulted in a fragment of mol. wt. 39 000 which still contained the steroid binding site but had increased affinity for DNA indistinguishable from that of the nti receptor. Chymotrypsin thus removed a domain from the wild-type receptor polypeptide which is involved in modulating DNA binding. The same domain is missing from the nti receptor.
