Ovine prolactin. Isoelectricfocusing and characterization of the separated components.

Highly purified ovine prolactin was subjected to preparative isoelectricfocusing. Although complete separation of the isoelectrically different components was not achieved, four enriched fractions of these components were prepared by this method. Studies on the separated fractions revealed that these components of ovine prolactin, probably a result of deamidation processes, have rather different properties. The more acidic components appeared to be less active in both the radioreceptor assay on mammary gland membranes and the pigeon crop-sac assay. However, the more acidic forms appeared to be more immunoreactive as revealed by radioimmunoassay.