A @entity1 @entity4311 - @entity1 @entity23151 ( @entity4311 . @entity23151 ) complex of approximately 1:1 stoichiometry ( @entity1 MutSbeta (hMutSbeta)) has been demonstrated in several @entity1 @entity5 cell lines and purified to near homogeneity. In vitro, hMutSbeta supports the efficient repair of insertion/deletion (I/D) heterologies of 2-8 @entity2036 , is weakly active on a single-nucleotide I/D mispair, and is not detectably active on the eight base-base mismatches. @entity1 MutSalpha (hMutSalpha), a heterodimer of @entity4311 and @entity4638 , efficiently supports the repair of single-nucleotide I/D mismatches, base-base mispairs, and all substrates tested that were repaired by hMutSbeta. Thus, the repair specificities of hMutSalpha and hMutSbeta are redundant with respect to the repair of I/D heterologies of 2-8 @entity2036 . The hMutSalpha level in repair-proficient HeLa cells (1.5 microg/mg nuclear extract) is approximately 10 times that of hMutSbeta. In HCT-15 @entity14 cells, which do not contain @entity4638 and consequently lack hMutSalpha, the hMutSbeta level is elevated severalfold relative to that in HeLa cells and is responsible for the repair of I/D mismatches that has been observed in this cell line. @entity5 cells, which are genetically deficient in @entity4311 , lack both hMutSalpha and hMutSbeta, and @entity23151 and @entity4638 levels are less than 4% of those found in repair-proficient cells. Coupled with previous findings (J. T. Drummond, J. Genschel, @entity69650 , and P. Modrich (1997) Proc. Natl. Acad. Sci. U. S. A. 94, 10144-10149), these results suggest that @entity4311 partitions between available pools of @entity23151 and @entity4638 and indicate that @entity4311 positively modulates @entity4638 and @entity23151 levels, perhaps by stabilization of the polypeptides upon heterodimer formation.

Isolation of MutSbeta from XXXX cells and comparison of the mismatch repair specificities of MutSbeta and MutSalpha.

@entity1 :: ('9606', 'Species') :: ['human', 'Human'] @entity2036 :: ('MESH:D009711', 'Chemical') :: ['nucleotides'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumor', 'LoVo tumor'] @entity69650 :: ('443256', 'Species') :: ['E. Wolf'] @entity4311 :: ('4436', 'Gene') :: ['hMSH2', 'MSH2'] @entity23151 :: ('4437', 'Gene') :: ['hMSH3', 'MSH3'] @entity14 :: ('MESH:D015179', 'Disease') :: ['colorectal tumor'] @entity4638 :: ('2956', 'Gene') :: ['hMSH6']
@entity1 :: (9606,Species) :: ['human']
