On the factors affecting the initiation of protein synthesis in the rat ventral prostate: Androgens, polyamines and conjugated proteins

Abstract

In the ventral prostate of certain strains of rats, androgens may have a very rapid effect on the initiation of protein synthesis by an antiandrogen sensitive process that may not be dependent on the synthesis of new RNA or protein. The primary effect appears to be at the step of met-tRNA f binding to the initiation factor EIF-1. Several stimulatory and inhibitory factors that can affect initiation factor activity are present in the prostate cytosol fraction. The low molecular weight inhibitory fraction contains polyamines which, at concentrations below 0.01 mM, can significantly inhibit this activity. The macromolecular effector fraction contains conjugated proteins (prostin H) that can destabilize met-tRNA f binding to initiation factor(s) and can also stimulate the incorporation of met-tRNA f into the newly synthesized protein. Upon enzymatic or acid proteolysis, prostin H releases the inhibitory components which behave like polyamines. It is possible that certain specific protein-bound polyamines play important roles in the hormonal regulation of protein synthesis in mammalian cells.