Fig. 3.

The high MW species of HCN1 isoforms is preferentially co-immunoprecipitated with the HCN2 isoform. Two samples of hippocampal homogenates (S1 and S2) have been subjected to immunoprecipitation either with anti-HCN1 (left panels) or with anti-HCN2 sera. The precipitate was then probed for HCN1 immunoreactivity using western blots. Two species of the HCN1 channels, of low and high apparent MWs, were precipitated with anti-HCN1, as expected. In contrast, the HCN1 species that co-immunoprecipitated with anti-HCN2 was primarily of a higher MW, i.e. glycosylated. This indicates that stable complexes (heteromeric channels) with HCN2 are formed mainly by glycosylated HCN1 channel molecules.