Effect of basic compounds on the polymerization of clathrin.

The effects of several divalent cations, various polybasic amines, and lysozyme on the rate of polymerization of 8S clathrin to the 300S coat structure have been evaluated by turbidimetric procedures. Ca2+ and Mn2+ strongly enhance the rate of polymerization. Only spermine among the naturally occurring polybasic amines had an important effect. Of the several basic proteins evaluated, only lysozyme stimulated the rate of polymerization. Some of these substances were able to increase the rate sufficiently so that polymerization occurred at physiological pH values. Without these compounds, clathrin will only polymerize at pH values of 6.8 or less.