AJP - Cell Physiology, Vol 248, Issue 1 80-C87, Copyright © 1985 by American Physiological Society
Specific binding sites for ovine prolactin in three amphibian cell lines
M. Dunand, M. L. Aubert, J. P. Kraehenbuhl and B. C. Rossier
Established cell lines (TB-6c and TB-M) obtained by continuous culture of
epithelial cells from toad Bufo marinus urinary bladder, which, in culture,
maintained a high degree of functional differentiation, exhibited a
significant number of high-affinity (KA = 1-2 X 10(10) M-1) binding sites
detected both with radioiodinated (125I) ovine prolactin (oPRL) and human
growth hormone (hGH). Binding capacity was higher in the case of TB-6c
cells (7,573 +/- 581 sites/cell) than with the TB-M cells (1,160 +/- 87).
Similarly, binding sites for oPRL were characterized on Xenopus laevis
kidney-derived cell line A6. With oPRL used both as tracer and standard,
significant cross-reaction was observed with hGH, less with human or rat
prolactin (PRL), and none with human chorionic somatomammotropin, bovine
growth hormone, and rat luteinizing hormone or follicle-stimulating
hormones. B. marinus pituitary extracts completely displaced the binding of
125I-oPRL to toad bladder binding sites. This finding of specific sites for
PRL on amphibian bladder and kidney cells confirms that PRL exerts specific
biological actions for the control of electrolyte and water metabolism in
the amphibians.
