Specific internalization of estrogen and binding to nuclear matrix in isolated uterine cells.
Fractionation of rat uterine cells incubated at 22 degrees C with 0.2 nM [3H]-estradiol-17 beta (E2 beta) was performed to analyze the subcellular distribution of internalized hormone. The postnuclear supernatant of homogenates was resolved in Percoll density gradients into six major fractions defined by enzyme markers. Within 10 s, E2 beta concentrates at the density of plasma membranes and also at a more buoyant density (p = 1.052 +/- 0.001) with peak accumulation of hormone by 2 min. Thereafter, binding in the latter fraction declines concomitantly with appearance of a portion of hormone at higher densities corresponding to Golgi and lysosomes. E2 beta exhibits preferential accumulation in nuclear matrix from 5 to 60 min. Microfiltration and scanning electron microscopy of the buoyant 2-min peak fractions reveal organelles, 50-200 nm. These may represent endocytotic vesicles that serve as vehicles for nuclear transfer of hormone.
D000818:Animals; D002369:Castration; D002458:Cell Fractionation; D002467:Cell Nucleus / Q000378:metabolism*; D002499:Centrifugation, Density Gradient / Q000379:methods; D004958:Estradiol / Q000378:metabolism*; D005260:Female; D051381:Rats; D011959:Receptors, Estradiol; D011960:Receptors, Estrogen / Q000302:isolation & purification / Q000378:metabolism*; D014599:Uterus / Q000378:metabolism*
D011959:Receptors, Estradiol; D011960:Receptors, Estrogen; D004958:Estradiol