title: Developmental changes in membrane protein expression by chick lens cells in vivo and in vitro and the detection of main intrinsic polypeptide (MIP).
abstract: We have compared the long-term developmental changes in water-insoluble protein expression by chick lens cells in vitro and in vivo. Crude membrane fractions were prepared by alkali treatment of the urea-insoluble protein fraction, and the proteins analysed by sodium dodecyl sulphate-polyacrylamide (SDS-PAGE) gel electrophoresis. The major component present in the urea-insoluble fraction of chick lens fibres, a 25,000 MW polypeptide (MIP-25K) was more abundant in adult (8 weeks) than day-old post-hatch chick lens fibre masses. MIP-25K was detected in differentiated but not predifferentiated lens cell cultures, and indirect immunofluorescence using anti-bovine MIP antiserum indicated that MIP-25K was localized in the lentoid bodies. Our findings indicate that the urea-insoluble protein profiles of long-term well-differentiated chick lens cell cultures are qualitatively very similar to the profiles of the lens fibres. The data also confirm that the expression of MIP-25K, rather than the expression of water-soluble crystallin protein, is a marker for lens cell differentiation, and confirm earlier reports, which have been disputed, that delta-crystallin (but not alpha-or beta-crystallin) is specifically associated with chick lens fibre membranes.
mesh_terms: D000375:Aging; D000818:Animals; D020346:Aquaporins; D002454:Cell Differentiation; D002478:Cells, Cultured; D002645:Chickens; D003459:Crystallins / Q000096:biosynthesis*; D004591:Electrophoresis, Polyacrylamide Gel; D005136:Eye Proteins / Q000096:biosynthesis* / Q000302:isolation & purification; D005779:Immunodiffusion; D007908:Lens, Crystalline / Q000378:metabolism; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000096:biosynthesis*; D008970:Molecular Weight; D010455:Peptides / Q000302:isolation & purification
chemical_list: D020346:Aquaporins; D003459:Crystallins; D005136:Eye Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D010455:Peptides; C030328:aquaporin 0