%0 Journal Article %T Novel isoform of adaptor protein ITSN1 forms homodimers via its C-terminus %A Dergai M. V. %A Dergai O. V. %A Tsyba L. O. %A Novokhatska O. V. %J Biopolymers and Cell %D 2011 %I Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine %X Aim. Previously we have identified a novel isoform of endocytic adaptor protein ITSN1 designated as ITSN122a. Western blot revealed two immunoreactive bands of 120 and 250 kDa that corresponded to ITSN1-22a. The goal of this study was to investigate the possibility of dimer formation by the novel isoform. Methods. Dimerization ability of ITSN1-22a was tested by immunoprecipitation and subsequent Western blot analysis. To specify the region responsible for dimerization, site-directed mutagenesis and truncation analysis were carried out. Inhibition of endocytosis by potassium depletion and EGF stimulation of HEK293 were performed. Results. We have found that ITSN1-22a forms dimers in HEK293 cells. The dimerization of ITSN1-22a was mediated by C-terminal domain. We showed that cysteines C1016 and C1019 were involved in homodimerization. Inhibition of clathrin-mediated endocytosis and mitogen stimulation did not affect ITSN1-22a dimer formation. Conclusions. ITSN1-22a is the only one known ITSN1 isoform, which is capable to form homodimers via disulphide bonds. This could be important for the formation of protein complexes containing ITSN1 molecules. %K intersectin 1 %K isoform %K homodimer %U http://biopolymers.org.ua/archive/2011/04/11.pdf