Effects of αC mutations on inhibin A biosynthesis. A,
hydrophobic residues in the inhibin αC (mature) domain were substituted
with alanine using in vitro mutagenesis. Pro, prodomain. To
determine the effects of amino acid substitutions on inhibin A production,
culture medium (B) and cell lysate (C) from CHO cells
transfected with either wild type (lane 1) or mutant α-subunit
(lanes 2–9), in combination with the
βA-subunit, were analyzed by Western blot. Samples were
detected with the R1 mAb, specific for the inhibin αC domain. The 31-kDa
inhibin A dimer, 52-kDa free α-subunit, and higher molecular mass
inhibin precursors forms are noted. D, the effect of αC
mutagenesis on inhibin A expression in CHO culture medium was also determined
by ELISA (* = p < 0.05). WT, wild type.