J. Biol. Chem., Vol. 259, Issue 8, 4833-4839, Apr, 1984
Characterization of the glucocorticoid receptor. Comparison of wild type and variant receptors
DJ Gruol, ES Kempner and S Bourgeois
We have measured the size of the glucocorticoid receptors from two murine
lymphoid cell lines, one displaying a wild type cytolytic response to
hormone, the other a resistant variant. Using radiation inactivation and
target analysis, we first compared the nuclear and cytoplasmic forms of the
steroid receptors in a wild type line, WEHI 7.1 (W7). Within the variation
expected for this type of measurement (+/- 14%), the nuclear and
cytoplasmic forms have the same size, 75,000 and 79,000 daltons,
respectively. We have also measured the size of the receptor in a
hormone-insensitive "nuclear transfer-increased" (nti) variant (S49 143R).
In contrast to reports indicating that the nti phenotype is associated with
a much smaller cytoplasmic receptor, we found little or no difference in
sizes of translocated receptor in wild type and nti cells. We have found
significant differences, however, in the release of wild type and nti
receptors from nuclei by nuclease digestion, salt, and spermidine.
Approximately 80% of the nti receptor was readily released from nuclei
incubated with micrococcal nuclease, while only 40-50% of the wild type
receptor was released under similar conditions. The wild type nuclei also
contained a fraction of receptor (approximately 30%) which was resistant to
extraction by NaCl and spermidine. This fraction was greatly diminished in
the nti nuclei. Thus, a portion of the wild type receptors appears to be
stabilized within the nuclei, possibly through a type of interaction which
cannot be sustained by the nti receptor.