Separation of rat pituitary growth hormone and prolactin by SDS polyacrylamide gel electrophoresis

Isolation of growth hormone (GH) and prolactin (PRL) from rat pituitary homogenates and cell fractions was carried out by polyacrylamide gel electrophoresis using a high resolution Na dodecylsulfate (SDS) system. With this technique GH and PRL are resolved as discrete and well separated bands. The method appears particularly adequate for quantitative determinations of the hormones and of the hormone bound radioactivity not only in pituitary homogenates but also in isolated cell fractions, since the treatment with SDS results in the complete solubilization of all samples and therefore allows the electrophoretic migrations of all hormone molecules. Using the SDS gel system, it was also possible to estimate the degree of contamination by nonhormone proteins in GH and PRL bands separated by the usual method of Ornstein and Davis.