Changes in membrane protein pattern in relation to lens cell differentiation

Newly Synthesized Proteins in a Cell-Free System Supplemented with Human and Bovine Membrane-Bound Polysomes Isolated from Lens Fiber Cells

“…1, b). Bands corresponding to vimentin, actin, MP34 and MP26 were identified on the basis of literature data [Vermorken et al, 1977;Ramaekers et al, 1980a], For comparison, one-dimensional pat terns of newly synthesized products from bovine lenses are shown in figure 2. In the lane of free polysomes ( fig.…”

Lens Proteins as Markers of Terminal Differentiation

“…In earlier studies we were able to show that addition of isolated lens polysomes to cell-free systems [ Vermorken et al, 1977] resulted in the syn thesis of the crystallins and one of the predominant plasma membrane pro teins MP34. However, the synthesis of the main fiber plasma membrane component MP26 could not be detected.…”

“…From our studies it appeared that epithelial plasma membranes largely resemble in protein pattern the lens fibers but there is a notable difference: the major constituent of fiber plasma membranes, a 26,000 molecular weight protein, is absent in epithelial plasma membranes ( fig.2) [Vermorken el at., 1977], As far as the predominance of [Alcalci et al, 1975], Broekhuyse [Broekhuyse and Kuhlmann, 1978] and recently by the groups of Kinoshita [Horwitz el a!., 1979] ans Spector [Roy el a i, 1979] in human lenses. Clayton and co-workers found MP26 in chick lens plasma membrane [Odeigah et al, 1979].…”

In vitro synthesis of the major lens membrane protein.

“…This is rather striking because polyribosomes that direct the synthesis of the other characteristic intrinsic membrane protein, MP34, are obtained by this method (8). In the present paper we demonstrate that this failure was due to the fact that the polyribosome fraction preferentially synthesizing MP26 is not "free" but seems to be associated with the plasma membrane-cytoskeleton complex in lens fibers.…”