Organ Specificity with Special Reference to the Lens (Part 1 of 3)

Abstract

Organ specificity and species specificity represent extremes of a spectrum of differentiation. The lens is characteristic of one end of this spectrum, and the proteins in this structure appear to be extremely stable in the evolutionary sense. At the other end of the spectrum lie some of the serum proteins, and probably some enzymes. Certain serum proteins, however, have been shown to be much more widely "organ-specific" than had been heretofore suspected. The evidence suggests that the rapidity or slowness of the biochemical evolutionary divergence of particular macromolecules determine the range of organ specificity. The extensive immumological data which have been accumulated on the lens make it possible to speculate reasonably about the biochemical evolutionary pathways of lens proteins. The observations may also clarify some of the uncertainty regarding the evolutionary position of various classes or species. Ultimately, it may be expected that protein isolations of analogous lens antigens from different species will be carried out, and that comparisons can then be made of the intimate structures by fingerprint analysis and amino acid sequence determinations. It may be hoped that the latter type of study will bring an understanding of evolutionary events at a molecular level. The present report makes it clear that large gaps of knowledge exist in the area, expecially since most authors have failed to study species representative of phylogenetic relationships. There is a great need for more systematic examination of organ-specificity as an expression of evolution.