Ca2+ binding sites in plasma membranes of rat liver and hepatoma cells, and effect of concanavalin A on the Ca2+ binding sites and cellular uptake of Ca2+.

Abstract

1. Plasma membranes isolated from rat livers and ascites hepatoma cells (AH-130, AH-7974) were assayed for specific Ca2+ binding sites using 45Ca2+ and a Millipore filtration technique. The presence of higher (Kd = 1.4--1.5 . 10(-5) M) and lower (Kd = 0.9--1.0 . 10(-4) M) affinity sites in both liver and hepatoma membranes was observed. The hepatoma plasma membranes however, showed 1.4--2.1-fold as many Ca2+ binding sites (higher and lower affinity sites) as the liver plasma membranes on the basis of protein. 2. Concanavalin A stimulated the specific Ca2+ binding to liver and hepatoma plasma membranes, showing a maximal stimulation (3--5-fold) at 100 microgram/ml. Succinyl concanavalin A was less effective, whereas wheat germ agglutinin and ricinus lectin were ineffective. 3. Concanavalin A stimulated the Ca2+ uptake by AH-7974 cells. The concanavalin A-mediated stimulation of Ca2+ uptake showed lectin-concentrations and Ca2+-concentration dependencies similar to those in the concanavalin A-mediated stimulation of Ca2+ binding.

• Authors: K Yamagami, H Terayama
• Journal: Biochimica et biophysica acta (Biochim Biophys Acta) Vol. 558 Issue 2 Pg. 199-213 (Dec 04 1979) ISSN: 0006-3002 [Print] Netherlands
• PMID: 508744 (Publication Type: Journal Article)

Chemical References

• Lectins
• Concanavalin A
• Calcium

Topics

• Animals
• Binding Sites
• Biological Transport (drug effects)
• Calcium (metabolism)
• Cell Line
• Cell Membrane (drug effects)
• Concanavalin A (pharmacology)
• Kinetics
• Lectins (pharmacology)
• Liver (metabolism)
• Liver Neoplasms, Experimental (metabolism)
• Male
• Rats
• Stimulation, Chemical