Cloning, chromosomal location, and expression analysis of murine Smarce1-related, a new member of the high-mobility 365 group gene family

Proteins containing high-mobility group (HMG) domains are segregated into t wo major groups. Members of one group are identified by the presence of mor e than one HMG domain that binds to DNA without sequence specificity, and t hey are usually ubiquitously expressed. In contrast, members of the other g roup possess a single HMG domain with high affinity to specific DNA sequenc es. Generally, members of the second group resemble classic tissue-specific transcriptional regulators. In contrast, Smarce1/BAF-57 is a ubiquitously expressed, novel protein with a single HMG domain that displays nonspecific DNA-binding characteristics. Additionally, as a core subunit of the mammal ian SWI/SNF-like transcriptional activator complex, Smarce1/BAF-57 is also the first member of the HMG protein family that was reported to contain a k inesin-like coiled-coil (KLCC) domain. Here we report the cloning, as well as the chromosomal and phylogenetic analysis, of a novel mammalian protein that is structurally related to Smarce1, termed Smarce1-related (Smarce1r). The unique arrangement of an HMG with a KLCC domain shared with Smarce1/BA F-57 suggests a similar, albeit still unknown, function in chromatin assemb ly as part of a mammalian SWI/SNF-like complex. The linkage of a single non specific DNA-binding HMG domain with a KLCC domain makes both proteins the founding members of a third group of HMG proteins. (C) 1999 Academic Press.