THE C-TERMINAL HALF OF THE PORCINE ESTRADIOL-RECEPTOR CONTAINS NO POSTTRANSLATIONAL MODIFICATION - DETERMINATION OF THE PRIMARY STRUCTURE

The C-terminal part of ligand filled porcine estradiol receptor extending from H-267 to I-595 was isolated by adsorption to the monoclonal antibody 13H2, subjected to cleavage by CNBr, o-iodosobenzoic acid and endopeptidase Lys-C as well as other proteases, both in the native and the denatured state. The overlapping peptides produced were separated by reverse phase HPLC and sequenced by Edman degradation, lacking T-570-M(581) in domain E We found no evidence of post-translational modification; the native fragment is not glycosylated and the tyrosyl residues in domain E (aa 328, 331, 459, 526, 537) and F (aa 582, 583) are not phosphorylated. In addition, all serine and threonine PTH derivatives were obtained in normal yields. The amino acid sequence of the fragment corresponds in full with that derived from the cDNA. The complete cDNA-derived sequence codes for a polypeptide of 595 amino acids with a calculated mass of 66 357 Da. The high degree of homology between species in domains C and E is shared by the porcine receptor.