Glycosylated Human Prolactin*

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Abstract
A glycosylated form of human PRL [prolactin] (G-hPRL) was isolated from pituitary glands. The glycoprotein was separated from the major form of PRL on columns of lentil lectin-Sepharose 4B. The major form of PRL did not bind to the lentil lectin, whereas the glycosylated modification did not count be eluted with methyl-.alpha.-D-mannopyranoside. By gel electrophoresis in sodium dodecyl sulfate, a MW of 25,000 was estimated for the glycosylated PRL. The MW of hPRL is 23,000. In a RIA [radioimmunoassay] for hPRL, the glycosylated hormone was about 1/3 as reactive as the principal form. Since there is only 1 Asn-X-Ser(Thr) sequence in hPRL, the asparagine at position 31 is the likely point of N-linked glycosylation.