STUDIES ON THE STRUCTURE AND FUNCTION OF THE CARP GONADOTROPIN ALPHA-SUBUNIT BY SITE-DIRECTED MUTAGENESIS

There are two genes encoding the alpha subunit of carp gonadotropin (a lpha(1) and alpha(2) subunits). Our previous data have demonstrated th at both alpha(1) and alpha(2) subunits expressed in insect cells are a ble to associate with the beta subunit, but only the alpha(1)/beta het erodimer displays biological activity. In the mature protein, there ar e only four amino-acid residues different between the alpha(1) and alp ha(2) subunits. In this study we used site-directed mutagenesis and ex pressed different mutant a subunits in insect cells to identify which residue might be important for biological activity of the a subunit. O ur results suggested that the change of Arg-71 to Gln-71 affected the activity of the carp gonadotropin a subunit. (C) Munksgaard 1995.