Dissociation of lens fibre gap junctions releases MP70.

MIP and MP70 are putative gap junction components in the plasma membranes of the mammalian lens fibre cells. We show now that MP70 can be solubilized separately from MIP in mild detergent solutions, and that this treatment results in the dissociation of the fibre gap junctions. Solubilized MP70 was isolated as 16.9 S particles by velocity gradient centrifugation and in the electron microscope had the appearance of short double-membrane structures consistent with connexon-pairs. These observations open a new experimental avenue in which to characterize separately the two putative lens gap junction proteins structurally and functionally.