@entity291 lens calmodulin. Isolation, partial characterization and XXXX -independent binding to lens membrane proteins.

@entity794 @entity2975 @entity460 @entity4329 @entity291 @entity214
Calmodulin has been isolated from @entity291 lens fiber cells. Like other vertebrate calmodulins lens calmodulin shows a @entity460 -dependent mobility shift on @entity214 - @entity2975 gels and forms immune complexes with antiserum, raised against vertebrate calmodulin. Via the gel overlay technique radioiodinated calmodulin from lens or @entity291 brain was found to bind to the @entity4329 ( @entity4329 ) and the 17.5 kDa protein of lens fiber membranes in a @entity460 -independent manner. After proteolytic digestion of lens fiber membranes with trypsin or @entity794 V8 protease the calmodulin-binding activity of @entity4329 is retained. This result indicates that the small polypeptide fragment of @entity4329 , which is accessible to proteolytic attack, apparently is not the attachment point for calmodulin. Two additional calmodulin-binding proteins (MW 14 kDa and 16.5 kDa) are observed in junction-enriched fiber membrane fractions. These junction-specific proteins are bound to the membrane via @entity460 . In addition to @entity4329 and the 17.5 kDa protein they are possibly involved in the @entity460 -dependent regulation of lens fiber junctions. The 14 and 16.5 kDa proteins are also present in epithelial membranes, prepared from freshly obtained @entity291 lens epithelia. Whereas in the latter membranes the two proteins form part of the four 14-17 kDa major protein components, these proteins are absent in membranes from cultured lens epithelial cells. The epithelial 14 kDa and 16.5 kDa proteins thus appear to be junction-specific. The capacity of the latter proteins to bind calmodulin in the presence and absence of @entity460 indicates that these junction-specific proteins are very similar, if not identical, to the corresponding fiber junctional proteins.(ABSTRACT TRUNCATED AT 250 WORDS)
