title: alpha m-Crystallin: the native form of the protein?
abstract: Evidence is presented that alpha-crystallin isolated at 37 degrees C exists as a species, alpha m, which has a minimum molecular weight of about 320000 and a sedimentation coefficient of about 12 S. The amino acid composition, subunit distribution, near- and far-UV CD spectra and immunochemical properties were identical to those of the previously studied, 19 S protein, alpha c-crystallin (minimum molecular weight, 635000). It was demonstrated that only alpha m-crystallin was present in 37 degrees C lens extracts and that cooling of lenses or extracts resulted in a conversion of alpha m- to alpha c-crystallin. This conversion appears to be a general phenomenon, independent of age or species. It was concluded that alpha c-crystallin is an aggregate, produced by cooling, and that alpha m-crystallin is more likely to represent the in vivo form of the protein.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002417:Cattle; D002850:Chromatography, Gel; D002942:Circular Dichroism; D003459:Crystallins / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007525:Isoelectric Focusing; D007614:Macropodidae; D008970:Molecular Weight; D011817:Rabbits; D013696:Temperature; D014461:Ultracentrifugation
chemical_list: D000596:Amino Acids; D003459:Crystallins