Characterization of a Novel Human SMC Heterodimer Homologous to the Schizosaccharomyces pombe Rad18/Spr18 Complex

EM Taylor, JS Moghraby, JH Lees, B Smit… - Molecular biology of …, 2001 - Am Soc Cell Biol
EM Taylor, JS Moghraby, JH Lees, B Smit, PB Moens, AR Lehmann
Molecular biology of the cell, 2001Am Soc Cell Biol
The structural maintenance of chromosomes (SMC) protein encoded by the fission yeast
rad18 gene is involved in several DNA repair processes and has an essential function in
DNA replication and mitotic control. It has a heterodimeric partner SMC protein, Spr18, with
which it forms the core of a multiprotein complex. We have now isolated the human
orthologues of rad18 and spr18 and designated them hSMC6 and hSMC5. Both proteins are
about 1100 amino acids in length and are 27–28% identical to their fission yeast …
The structural maintenance of chromosomes (SMC) protein encoded by the fission yeast rad18 gene is involved in several DNA repair processes and has an essential function in DNA replication and mitotic control. It has a heterodimeric partner SMC protein, Spr18, with which it forms the core of a multiprotein complex. We have now isolated the human orthologues of rad18 andspr18 and designated them hSMC6 andhSMC5. Both proteins are about 1100 amino acids in length and are 27–28% identical to their fission yeast orthologues, with much greater identity within their N- and C-terminal globular domains. The hSMC6 and hSMC5 proteins interact to form a tight complex analogous to the yeast Rad18/Spr18 heterodimer. In proliferating human cells the proteins are bound to both chromatin and the nucleoskeleton. In addition, we have detected a phosphorylated form of hSMC6 that localizes to interchromatin granule clusters. Both the total level of hSMC6 and its phosphorylated form remain constant through the cell cycle. Both hSMC5 and hSMC6 proteins are expressed at extremely high levels in the testis and associate with the sex chromosomes in the late stages of meiotic prophase, suggesting a possible role for these proteins in meiosis.
Am Soc Cell Biol