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Prolactin-binding sites in tilapia (Sarotherodon mossambicus) kidney

1979; Elsevier BV; Volume: 39; Issue: 3 Linguagem: Inglês

10.1016/0016-6480(79)90137-0

1095-6840

James N. Fryer,

Growth Hormone and Insulin-like Growth Factors

Highly purified 125I-labeled tilapia (Sarotherodon mossambicus) prolactin (PRL) binds to microsomal membrane fractions prepared from tilapia kidney but not liver or gill. Specificity studies revealed that up to 35% of the labeled tilapia PRL bound to the kidney membrane preparation could be displaced by 100 ng of unlabeled hormone. Ovine PRL displaced 125I-labeled tilapia PRL from the kidney PRL-binding site. However, 125I-labeled ovine PRL demonstrated negligible specific binding to microsomal membrane fractions of tilapia kidney, liver, gill, or muscle. Tilapia PRL did not inhibit the binding of 125I-labeled ovine PRL to lactating rat liver membranes. The specific binding of 125I-labeled tilapia PRL to tilapia kidney membranes was greater with freshwater-acclimated than with seawater-acclimated fish suggesting that the tilapia kidney PRL-binding site is subject to physiological regulation.