title: C-terminal proteolysis of the avian 1,25-dihydroxyvitamin D3 receptor.
abstract: Exposure of the 60 kDa chick intestinal 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) receptor to carboxypeptidase A resulted in a time dependent decrease in receptor hormone-binding; after 2 h, there was no detectable macro-molecular-bound 1,25(OH)2[3H]D3. Upon DNA-cellulose chromatography of this preparation, a 56 kDa protein adsorbed to the column and eluted as a function of para-chloromercuribenzene sulfonate (a sulfhydryl blocking reagent). The 56 kDa fragment was detected by anti-receptor monoclonal antibodies via immunoblot technology. The 1,25(OH)2[3H]D3 eluted in the fall through fractions of the column. Thus, cleavage of up to 40 amino acids from the carboxy-terminus of the 1,25(OH)2D3 receptor results in a protein which no longer binds to hormone, but retains its capacity to interact with DNA-cellulose and monoclonal antibody. These results represent novel biochemical evidence that allows us to orient the 1,25(OH)2D3 binding domain near the C-terminus of the receptor.
authors.forename: E A
authors.initials: EA
authors.lastname: Allegretto
authors.forename: J W
authors.initials: JW
authors.lastname: Pike
authors.forename: M R
authors.initials: MR
authors.lastname: Haussler
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D001665:Binding Sites; D002117:Calcitriol / Q000378:metabolism*; D002268:Carboxypeptidases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000276:immunology / Q000502:physiology*; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000276:immunology / Q000502:physiology*; D013329:Structure-Activity Relationship
chemical_list: D000911:Antibodies, Monoclonal; D004268:DNA-Binding Proteins; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D002268:Carboxypeptidases; D002117:Calcitriol