Increase of (Ca2+ +Mg2+)-ATPase activity of renal basolateral membranes by platelet-derived growth factor through a specific receptor.
Studies were made on the direct effect of platelet-derived growth factor (PDGF) on the high-affinity (Ca2+ +Mg2+)-ATPase, a membrane bound Ca2+-extrusion pump enzyme of the basolateral membranes (BLM) of canine kidney (Km for free Ca2+ = 1.0 x 10(-7) M, Vmax = 180 nmol Pi/mg/min). At 1 x 10(-7) M free Ca2+, PDGF (10(-10)-10(-8) M) stimulated the enzyme activity significantly. Addition of 5 - 200 microM suramin, a compound that blocks binding of PDGF to its receptors on cell membranes, inhibited the stimulatory effect of PDGF dose-dependently (IC50 = 40 microM). A high affinity specific receptor for PDGF (Kd = 4.4 x 10(-10) M, Bmax = 460 fmol/mg protein) was detected on BLM preparations by radioreceptor assay with 125I-PDGF and unlabelled PDGF. Suramin (10-1000 microM) also inhibited the binding of PDGF to BLM preparations dose-dependently. From these results, it is proposed that PDGF stimulates (Ca2+ +Mg2+)-ATPase activity of kidney BLM preparations by enhancing its affinity for free Ca2+ through a specific receptor.
Itoh
K
K
Department of Medicine and Geriatrics, Osaka University Medical School, Japan.
Morimoto
S
S
Shiraishi
T
T
Taniguchi
K
K
Onishi
T
T
Kumahara
Y
Y
D000818:Animals; D001485:Basement Membrane / Q000201:enzymology; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D007668:Kidney / Q000648:ultrastructure*; D008970:Molecular Weight; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017479:Receptors, Platelet-Derived Growth Factor; D013498:Suramin / Q000494:pharmacology
D010982:Platelet-Derived Growth Factor; D011956:Receptors, Cell Surface; D013498:Suramin; D017479:Receptors, Platelet-Derived Growth Factor; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases