SMC protein
InterPro Family
SMC proteins represent a large family of ATPases that participate in many aspects of higher-order chromosome organization and dynamics. SMC proteins are widely conserved across bacteria, archaea, and eukaryotes. In eukaryotes, they function as the core ATPase subunits of large protein complexes such as condensin, cohesin, and SMC5/6.
The term SMC derives from a mutant strain of Saccharomyces cerevisiae named smc1 (stability of mini-chromosomes 1), which was identified based on its defect in maintaining the stability of mini-chromosomes. After the gene product of SMC1 was characterized, and homologous proteins were found to be essential for chromosome structure and dynamics in many organisms, the acronym SMC was redefined to stand for "Structural Maintenance of Chromosomes".
Classification
Eukaryotic SMCs
Eukaryotes have at least six SMC proteins in individual organisms, and they form three distinct heterodimers with specialized functions:
SMC1-SMC3: A pair of SMC1 and SMC3 constitutes the core subunits of the cohesin complexes involved in sister chromatid cohesion.
SMC2-SMC4: A pair of SMC2 and SMC4 acts as the core of the condensin complexes implicated in chromosome condensation.
SMC5-SMC6: A pair of SMC5 and SMC6 functions as part of a yet-to-be-named complex implicated in DNA repair and checkpoint responses.
The pairings of SMC proteins in eukaryotes, SMC1-SMC3, SMC2–SMC4, and SMC5–SMC6, are highly specific and invariant; no exceptions to these combinations have been reported to date. Sequence comparisons reveal that SMC1 and SMC4, as well as SMC2 and SMC3, share a high degree of similarity, while SMC5 and SMC6 form a more distinct clade (Figure 1).
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This entry incorporates text from “SMC protein” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.