A protein binding to CArG box motifs and to single-stranded DNA functions as a transcriptional repressor

Gene. 1992 Oct 1;119(2):229-36. doi: 10.1016/0378-1119(92)90276-u.

Abstract

A CArG box motif [CC(A+T-rich)6GG] is one of the DNA elements required for muscle-specific gene transcription. Nuclear factors in mouse C2 myogenic cells strongly bind to the CArG box in the first intron of the gene (Sm alpha-A) encoding human smooth muscle alpha-actin. To clone cDNAs of the CArG box-binding factor (CBF), lambda gt11 cDNA expression libraries from C2 cells were screened for in situ DNA binding specific for this CArG box sequence. The 1.6-kb cDNA (CBF-A) encoding 285 amino acids (aa) was obtained, and a beta-galactosidase fusion protein, bacterially produced from the cDNA, bound to DNA fragments containing several CArG boxes. When the expression level of CBF-A in C2 cells increased by transfection of CBF-A expression plasmids, Sm alpha-A transcription was repressed. The deduced aa sequence of CBF-A is similar to some single-stranded (ss) nucleic acid-binding proteins. The fusion protein could bind to ssDNA, whereas CBF in C2 cell nuclear extracts could not. From these results, CBF-A is a novel CArG box-, ssDNA- and RNA-binding protein, as well as a repressive transcriptional factor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / genetics
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cell Line
  • Conserved Sequence
  • DNA, Single-Stranded / genetics
  • DNA, Single-Stranded / metabolism*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Heterogeneous-Nuclear Ribonucleoprotein Group A-B*
  • Mice
  • Molecular Sequence Data
  • Muscles / cytology
  • Muscles / metabolism*
  • Regulatory Sequences, Nucleic Acid*
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • Species Specificity

Substances

  • Actins
  • DNA, Single-Stranded
  • DNA-Binding Proteins
  • Heterogeneous-Nuclear Ribonucleoprotein Group A-B
  • Repressor Proteins
  • Hnrnpab protein, mouse

Associated data

  • GENBANK/D90151
  • GENBANK/L05337
  • GENBANK/M74891
  • GENBANK/M74892
  • GENBANK/M79309
  • GENBANK/M79310
  • GENBANK/M86534
  • GENBANK/M90357
  • GENBANK/S43297
  • GENBANK/X61715