IBN-9412115 Robert Dores The pituitary gland is the site for synthesis of several polypeptide hormones which are used as chemical messenger to influence a variety of functions such as growth, reproduction, and chronic stress regulation. One characteristic of polypeptide hormones is that the molecule that is first synthesized inside the cell (called a prohormone) is biologically inactive and must undergo a variety of processing steps by enzymes to convert the non-functional prohormone into a biologically active hormone. One of these important prohormones is proopiomelanocortin (POMC) found in the intermediate pituitary. POMC is the common prohormone for adrenocorticotropin, melanocyte-stimulating hormone, and the endogenous opioid, beta-endorphin. After POMC is synthesized, it undergoes a number of processing steps to make these active hormones. The sites inside the cell where the enzymatic reactions take place and the regulation and nature of the enzymes involved are poorly understood. This is a proposal to study in melanotropic cells of the anuran amphibian, Bufo marinus, the subcellular coordination of two important enzymes (prohormone convertase 1 and 2) that are involved in the processing and the location inside the cell where this processing occurs. Since the proper synthesis of pituitary hormones is essential to the survival of all vertebrates, these studies are critical for providing new insights into the cell biology of pituitary cells.
