Peculiarities of oligomerization of smooth muscle titin and skeletal myosin-binding protein C

Abstract

Protein oligomers are important intermediates in the formation of amyloid fibrils. In amyloidoses, for instance, in Alzheimer's disease, oligomers are able to exert toxic effects on cells. This paper describes the distinctive features of oligomerization of multidomain muscle proteins such as smooth muscle titin and myosin-binding protein C (MyBP-C) of skeletal muscles, which consist of FnIII-like and IgC2-like domains and form amorphous amyloid aggregates in vitro. MyBP-C at low ionic strength (below physiological values) formed stable oligomers that did not participate in further aggregation. In high ionic strength conditions (µ ~ 0.6), smooth muscle titin formed oligomers, which were precursors of amyloid amorphous aggregates of this protein. The results obtained help expand existing knowledge about the process of protein aggregation.