AND-1, a natural chimeric DNA-binding protein, combines an HMG-box with regulatory WD-repeats.
Using a specific monoclonal antibody (mAb AND-1/23-5-14) we have identified, cDNA-cloned and characterized a novel DNA-binding protein of the clawed toad, Xenopus laevis, that is accumulated in the nucleoplasm of oocytes and various other cells. This protein comprises 1,127 amino acids, with a total molecular mass of 125 kDa and a pI of 5.27. It is encoded by a mRNA of approximately 4 kb and contains, in addition to clusters of acidic amino acids, two hallmark motifs: the amino-terminal part harbours seven consecutive 'WD-repeats', which are sequence motifs of about 40 amino acids that are characteristic of a large group of regulatory proteins involved in diverse cellular functions, while the carboxy terminal portion possesses a 63-amino-acid-long 'HMG-box', which is typical of a family of DNA-binding proteins involved in regulation of chromatin assembly, transcription and replication. The DNA-binding capability of the protein was demonstrated by DNA affinity chromatography and electrophoretic mobility shift assays using four-way junction DNA. Protein AND-1 (acidic nucleoplasmic DNA-binding protein) appears as an oligomer, probably a homodimer, and has been localized throughout the entire interchromatinic space of the interphase nucleoplasm, whereas during mitosis it is transiently dispersed over the cytoplasm. We also identified a closely related, perhaps orthologous protein in mammals. The unique features of protein AND-1, which is a 'natural chimera' combining properties of the WD-repeat and the HMG-box families of proteins, are discussed in relation to its possible nuclear functions.
Köhler
A
A
Division of Cell Biology, German Cancer Research Center, Heidelberg, Germany.
Schmidt-Zachmann
M S
MS
Franke
W W
WW
D000818:Animals; D000911:Antibodies, Monoclonal; D002467:Cell Nucleus / Q000737:chemistry; D003429:Cross Reactions; D018076:DNA, Complementary / Q000032:analysis / Q000302:isolation & purification; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D005260:Female; D006609:High Mobility Group Proteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009865:Oocytes / Q000737:chemistry; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D012995:Solubility; D013045:Species Specificity; D029867:Xenopus Proteins; D014982:Xenopus laevis
D000911:Antibodies, Monoclonal; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D006609:High Mobility Group Proteins; D011993:Recombinant Fusion Proteins; C106931:WDHD1 protein, Xenopus; D029867:Xenopus Proteins