Radioimmunoreactivity and receptor-binding activity of the recombined molecule obtained by complementation of two fibrinolysin fragments of ovine prolactin.

The recombined molecule obtained by complementation of two fibrinolysin fragments of ovine prolactin (oPRL) has been characterized by radioimmunoassay and radioreceptor assay. The recombinant alone exhibits very low radioimmunoreactivity and radioreceptor activity. However, in the presence of excess fragment oPRL-(1-53), which does not compete with oPRL in either assay, the recombinant has 101% of the radioimmunoreactivity and only 13% of the radioreceptor activity. The result shows that the low activity of the recombinant when assayed alone is due to dissociation of the molecule. When the molecule is completely in the recombined form in the presence of excess oPRL-(1-53), it retains full immunoreactivity but only part of the radioreceptor activity.