Analysis of monomeric-dimeric states of the estrogen receptor with monoclonal antiestrophilins.
We studied the antibody-combining properties of 3 forms of the estrogen receptor found in buffers of high ionic strength. Shifts to a faster sedimenting peak on sucrose gradients or a faster eluting peak on a gel filtration column with antibody addition allowed us to determine whether a given form contained one, two or more antibody-binding sites. The monomeric cytosolic estrogen receptor, ERC, contained one antibody binding site for each of 2 monoclonal antiestrophilins (H222 and H165, provided by Abbott Laboratories). Both the heat-transformed cytosolic estrogen receptor, ERC*, and a major fraction of the estrogen receptor extracted from nuclei, ERN, contained two sites for H165, but only one for H222. A minor fraction of ERN had only one site for each antibody. The kinetics of transformation of ERC to a species with two H165 binding sites were appropriate to a dimerization of ERC*. Addition of H222, but not H165, before the onset of the heat-induced transformation blocked the formation of ERC to ERC. These data suggest that ERC* and a major form of ERN are comprised of two immunologically similar subunits identical to ERC. Also, the antigenic determinant for H222, but not H165, appears to be located close to the dimerization domain. The minor form of ERN appears to contain an altered or dissimilar subunit.
Linstedt
A D
AD
West
N B
NB
Brenner
R M
RM
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D002499:Centrifugation, Density Gradient; D002850:Chromatography, Gel; D000939:Epitopes / Q000032:analysis; D005260:Female; D008252:Macaca fascicularis; D008970:Molecular Weight; D011487:Protein Conformation; D011960:Receptors, Estrogen / Q000032:analysis* / Q000276:immunology / Q000378:metabolism; D013696:Temperature
D000911:Antibodies, Monoclonal; D000939:Epitopes; D011960:Receptors, Estrogen