Synthesis and secretion of a large glycoprotein in the pars intermedia.

The biosynthesis, intracellular transport and release of [3-H]-leucine-containing secretory product has been followed in the pars intermedia of Xenopus laevis and, in particular, the synthesis and secretion of a large molecular weight glycoprotein secretory product was demonstrated. However, if Xenopus adrenocorticotrophin does contain a leucine residue the results obtained provided no support for the view that it serves as a precursor for melanocytestimulating hormone in this species.