Biochemical characterization of plasma membrane isolated from human skeletal muscle.
Specific components of ion translocation systems were studied in excitable plasma membranes isolated from normal human muscle. Na+-K+ ATPase and ouabain-sensitive K+ phosphatase activities were 8.9 +/- 1 mumol Pi/h per mg protein and 96 +/- 9 nmol/min per mg protein, respectively. Scatchard analysis of equilibrium binding assays with [3H]ouabain showed non-linear curves consistent with high- and low-affinity sites (estimated Kd 3 nM and 0.22 microM). Two families of receptors with different affinities for a tritiated TTX derivative (estimated Kd 0.4 and 4 nM) were also identified suggesting the existence in human muscle of at least two classes of voltage-dependent Na+ channels. In addition (+)-[methyl-3H]PN200-110, a potent Ca2+ antagonist used for labeling voltage-dependent Ca2+ channels, was observed to bind to a homogeneous population of receptors in the plasma membrane (Kd = 0.2 nM).
C
C
Desnuelle
D
D
Liot
G
G
Serratrice
A
A
Lombet
D002121:Calcium Channel Blockers / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002458:Cell Fractionation; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D007473:Ion Channels / Q000378:metabolism; D017275:Isradipine; D008563:Membrane Lipids / Q000032:analysis; D008565:Membrane Proteins / Q000032:analysis; D009132:Muscles / Q000201:enzymology* / Q000378:metabolism; D010042:Ouabain / Q000494:pharmacology; D010069:Oxadiazoles / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D011955:Receptors, Drug / Q000378:metabolism; D015222:Sodium Channels; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D002121:Calcium Channel Blockers; D002352:Carrier Proteins; D007473:Ion Channels; D008563:Membrane Lipids; D008565:Membrane Proteins; D010069:Oxadiazoles; D011955:Receptors, Drug; D015222:Sodium Channels; C028996:cardiac glycoside receptors; C023790:tetrodotoxin-binding protein; D010042:Ouabain; D010744:Phosphoric Monoester Hydrolases; D000254:Sodium-Potassium-Exchanging ATPase; D017275:Isradipine