Cloning, characterization and localization of Chinese hamster HP1 isoforms

The Chinese hamster is one of the few mammalian species that are characterized by relatively poor heterochromatin content. It was intriguing to test whether or not the lack of large blocks of heterochromatin in the hamster chromosomes could be correlated with the absence or species-specific differences of the HP1 proteins, the main structural components of heterochromatin. To address this, we attempted to clone HP1 from the Chinese hamster. It is shown here that all three isoforms of HP1 known in mammals are present in hamster, and the amino acid sequences deduced from the cDNAs of the isoforms are 97–100% identical to those of the known mammalian homologues. All three isoforms are localized mainly in heterochromatic regions in the native chromosomes and nuclei. The hamster HP1α gene was cloned, sequenced and mapped to the short arm of hamster chromosome 2.