Chick heat-shock protein of Mr = 90,000, free or released from progesterone receptor, is in a dimeric form.

摘要: Abstract A monoclonal antibody (BF4) has been used to characterize and purify the heat-shock protein of Mr approximately 90,000 (hsp 90) present in chick oviduct. In low salt cytosol, sedimentation coefficient hsp 90 is 6.8 S, Stokes radius 7.1 nm, calculated 204,000, thus suggesting a dimeric structure. 0.4 M KCl only slightly smaller values were determined (approximately 6.5 187,000). Following purification by ion exchange immunoaffinity chromatography, migrated as single silver-stained band at sodium dodecyl sulfate-polyacrylamide gel electrophoresis, while 6.2 178,000 confirmed However, both antigen or excess conditions, one molecule could be bound dimer. Whether steric hindrance homodimer presence two different 90-kDa proteins heterodimer explains this result cannot yet decided. The dimer not dissociated high (1 KCl) chaotropic agent (0.5 NaSCN), but disrupted 4 urea, stabilization structure hydrogen bonds. molybdate-stabilized progesterone receptor hetero-oligomer form 8 S was purified, its component then released treatment. It found sediment 5.8 have giving 174,000. This observation consistent with previous report from specific activity determination, scanning polyacrylamide gels, cross-linking experiments that each purified nontransformed includes binding unit per molecules (Renoir, J. M., Buchou, T., Mester, J., Radanyi, C., Baulieu, E. (1984) Biochemistry 23, 6016-6023). work brings direct evidence free non-hormone steroid cytosol are form.