Preproparathyroid hormone

Figure 42-13. Structure of bovine preproparathyroid hormone. Arrows indicate sites cieaved by processing enzymes in the parathyroid giand (1-5) and in the iiver after secretion of the hormone (4-5). The bioiogicaiiy active region of the moiecuie is fianked by sequence not required for activity on target receptors. (Slightly modified and reproduced, with permission, from Habener JF Recent advances in parathyroid hormone research. Clin Biochem 1981 14 223.)...

Russell J et al Interaction between calcium and 1,25-dihydroxy-vitamin D3 in the regulation of preproparathyroid hormone and vitamin D receptor mRNA in avian parathyroids. Endocrinology 1993 132 2639. 

Figure 49-10 Amino acid sequence of preproparathyroid hormone. Arrows indicate the sites of cleavage by proteases to remove the N-terminal methionines (/), the leader (pre) sequence (2), and the pro sequence (3), producing intact PTH (1-84). Cleavage at position 4 produces inactive carboxyl (C)-terminai fragments. (From Habener JF, Rosenblatt Ni, Potts JT Jr. Parathyroid hormone Biochemical aspects of biosynthesis, secretion, action, and metabolism. Physiol Rev 1984 64 985-1053.)...

Austen et al. (1984) found that the consensus signal peptide inhibits protein translocation into RER microsomes. Synthetic preproparathyroid hormone signal sequence also decreased the translocation and processing of four prehormones in a cell-free translation system (Majzoub et al., 1980). Synthesis of the prehormones appears to be unaffected. Addition of a control peptide failed to inhibit processing. 

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