Isolation of cDNA encoding a binding protein specific to 5'-phosphorylated single-stranded DNA with G-rich sequences

摘要

We have isolated the cDNA encoding a binding protein to the sequence motif of the Immunoglobulin Sμ region by the southwestern method. The binding protein designated Sμbp-2 specifically binds to 5'-phos-phorylated single-stranded DNA containing 5'-G and GGGG stretches. The amlno acid sequence deduced from the the cDNA sequence showed that the Sμbp-2 belongs to the putative hellcase superfamlly which is involved in replication, recombination and repair. Expression of Sμbp-2 mRNA is ubiquitous and augmented In spleen cells stimulated with llpopolysaccharide and interteukln 4 which also Induce class switching. The Sμbp-2 gene Is conserved among vertebrates. Possible Involvement of Sμbp-2 in class switching is discussed.