Hydrodynamic characterization of the major intrinsic protein from the bovine lens fiber membranes. Extraction in n-octyl-beta-D-glucopyranoside and evidence for a tetrameric structure.
The major protein from the bovine lens fiber cell membranes, the 26-kilodalton protein (major intrinsic protein (MIP26)), has been solubilized in n-octyl-beta-D-glucopyranoside and purified by gel filtration. The final preparation was free of detergent micelles. Gel electrophoresis in denaturing conditions has confirmed the purity of the protein sample. A s20,w of 5.55 S, obtained from analytical ultracentrifugation, and a D20,w of 3.62 x 10(-7) cm2 s-1, obtained from photon correlation spectroscopy, resulted in a molar mass of (176,000 +/- 15,000) g/mol for the protein-detergent complex using the Svedberg relation. The measured detergent content of 0.71 g of detergent/g of protein resulted in a calculated partial specific volume of 0.787 cm3/g for the protein-detergent complex and a molar mass of 103,000 g/mol for the protein moiety. This allowed us to conclude that the protein-detergent complex contains four copies of the MIP26 protein, which supports the suggestion that in vivo the MIP26 molecules cluster in tetramers to form a pore-like structure.
Aerts
T
T
Department of Biochemistry, University of Antwerp, Belgium.
Xia
J Z
JZ
Slegers
H
H
de Block
J
J
Clauwaert
J
J
D000818:Animals; D020346:Aquaporins; D002417:Cattle; D002458:Cell Fractionation; D002462:Cell Membrane / Q000032:analysis; D003902:Detergents; D004591:Electrophoresis, Polyacrylamide Gel; D005136:Eye Proteins / Q000302:isolation & purification*; D005960:Glucosides; D007908:Lens, Crystalline / Q000032:analysis*; D008562:Membrane Glycoproteins / Q000302:isolation & purification*; D008823:Micelles; D008970:Molecular Weight; D013057:Spectrum Analysis
D020346:Aquaporins; D003902:Detergents; D005136:Eye Proteins; D005960:Glucosides; D008562:Membrane Glycoproteins; D008823:Micelles; C030328:aquaporin 0; C018619:octyl-beta-D-glucoside