Open AccessInteractions of plasma gelsolin with actin
Author(s) -
PORTE Françoise,
HARRICANE MarieCécile
Publication year - 1986
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1986.tb09362.x
Subject(s) - gelsolin , ternary complex , chemistry , actin , biophysics , egta , polymerization , stokes radius , ternary operation , chromatography , size exclusion chromatography , biochemistry , biology , organic chemistry , calcium , computer science , programming language , enzyme , polymer
We have studied the interactions between plasma gelsolin and actin: firstly the complex formation between both proteins, secondly the effects of gelsolin and its complexes on G‐actin polymerization and F‐actin fragmentation. Complex formation has been studied by high‐performance gel permeation chromatography; plasma gelsolin alone elutes at an M r of about 77000 and a Stokes radius of 3.7 nm; complex formation occurs in the presence of Ca 2+ : by chromatography in the presence of EGTA, a binary complex is obtained with an M r of 134000 and a Stokes radius of 4.7 nm; and by chromatography in the presence of Ca 2+ , a ternary complex is obtained with an M r of 173000 and a Stokes radius of 5.2 nm. The binary complex is EGTA‐stable. In relation to this stability of the binary complex, the depolymerizing function of gelsolin is not reversed upon chelation of Ca 2+ . The effects of plasma gelsolin and its complexes on both G‐actin polymerization and F‐actin fragmentation, and their Ca 2+ dependence have been examined by viscometry and electron microscopy. The main conclusions of these studies are the following: (a) the fast processes are the formation of ternary complex, which acts as a heteronucleus for G‐actin polymerization, and the severing function of gelsolin, these fast processes are Ca 2+ ‐dependent; (b) the slow processes are related to the capping ability of gelsolin or its complexes and are Ca 2+ ‐independent.