Estimate of the molecular weight of the sarcolemmal sodium channel using H2O-D2O centrifugation.
The sodium channel saxitoxin binding component from rat sarcolemma was solubilized with NP-40 and centrifuged on sucrose gradients constructed in either D2O or H2O. When compared with a series of standard proteins the sedimentation behavior of the solubilized channel complex changed from an apparent S20,w of 9.1 in H2O to 6.1 in D2O. From these observations, a true partial specific volume of 0.83 ml/g was calculated for the complex. A Stokes radius of 8.6 nm was estimated from Sepharose 6-B chromatography in NP-40. The calculated protein molecular weight of the lipid-protein-detergent complex based on these data is 560,000. The complex contains about 56% protein, and the calculated molecular weight of this component is 314,000 if a v for the protein of 0.74 ml/g is assumed.
D029845:Amphibian Proteins; D000818:Animals; D002352:Carrier Proteins / Q000302:isolation & purification*; D002499:Centrifugation, Density Gradient / Q000379:methods; D003902:Detergents; D003903:Deuterium; D007473:Ion Channels / Q000032:analysis*; D008970:Molecular Weight; D017830:Octoxynol; D011092:Polyethylene Glycols; D051381:Rats; D012508:Sarcolemma / Q000032:analysis*; D012530:Saxitoxin / Q000302:isolation & purification*; D012964:Sodium / Q000378:metabolism*; D014867:Water
D029845:Amphibian Proteins; D002352:Carrier Proteins; D003902:Detergents; D007473:Ion Channels; C027525:saxitoxin-binding protein, Rana catesbeiana; D014867:Water; D012530:Saxitoxin; D011092:Polyethylene Glycols; D017830:Octoxynol; C010615:Nonidet P-40; D012964:Sodium; D003903:Deuterium