Аннотация:The giant muscle protein, titin, is the third most abundant protein inmuscle (after myosin and actin). It was shown previously that smoothmuscle titin (SMT) with a molecular mass of 500 kDa can form in vitroamorphous amyloid aggregates in two conditions: in solution of lowionic strength (0.15MGlycine-KOH, pH7.0) (SMT(Gly) aggregates) andin solution with ionic strength in the physiological range (0.2 M KCl,20mMimidazole,pH 7.2–7.4) (SMT(KCl) aggregates). Such aggregationin vivo, which may play a pathological or functional role, is notexcluded. In view of the fact that some pathological amyloids canactivate the classical and alternative pathways of complement system,we investigated the binding of complement component C1q and C3bto smooth muscle titin amyloid aggregates. The binding of С1q andC3b to SMT aggregates was not observed with ELISA assay. Since SMTaggregates do not activate the complement system, they are hardlyimplicated in the inflammatory process caused by muscle damage inamyloidoses.