Expression of ID, a negative regulator of helix-loop-helix DNA binding proteins, is down-regulated at confluence and enhanced by dexamethasone in a mouse osteoblastic cell line, MC3T3E1

Recent studies have identified a family of DNA-binding proteins that share a common DNA-binding and dimerization domain with the potential to form a helix-loop-helix (HLH) structure. Various HLH proteins can form heterodimers that bind to a common DNA sequence, termed the E2-box. We demonstrate here that E2-box-binding B-cell- and myocyte-specific nuclear factors contain subunits which are identical or closely related to ubiquitously expressed (E12/E47) HLH proteins. These biochemical function for E12/E47-like molecules in mammalian differentiation, similar to the genetically defined function of daughterless in Drosophila development.

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Ligatoxin B, a new cytotoxic protein with a novel helix–turn–helix DNA-binding domain from the mistletoe Phoradendron liga

Biochemical Journal ◽

10.1042/bj20020221 ◽

2002 ◽

Vol 366 (2) ◽

pp. 405-413 ◽

Cited By ~ 24

Author(s):

Shi-Sheng LI ◽

Joachim GULLBO ◽

Petra LINDHOLM ◽

Rolf LARSSON ◽

Eva THUNBERG ◽

...

Keyword(s):

Dna Binding ◽

Cell Line ◽

Binding Proteins ◽

Molecular Mechanisms ◽

Homology Modelling ◽

Dna Binding Proteins ◽

Dimensional Structure ◽

Cytotoxic Activities ◽

Cytotoxic Action ◽

Working Hypothesis

A new basic protein, designated ligatoxin B, containing 46 amino acid residues has been isolated from the mistletoe Phoradendron liga (Gill.) Eichl. (Viscaceae). The protein's primary structure, determined unambiguously using a combination of automated Edman degradation, trypsin enzymic digestion, and tandem MS analysis, was 1–KSCCPSTTAR–NIYNTCRLTG–ASRSVCASLS–GCKIISGSTC–DSGWNH–46. Ligatoxin B exhibited in vitro cytotoxic activities on the human lymphoma cell line U-937-GTB and the primary multidrug-resistant renal adenocarcinoma cell line ACHN, with IC50 values of 1.8μM and 3.2μM respectively. Sequence alignment with other thionins identified a new member of the class 3 thionins, ligatoxin B, which is similar to the earlier described ligatoxin A. As predicted by the method of homology modelling, ligatoxin B shares a three-dimensional structure with the viscotoxins and purothionins and so may have the same mode of cytotoxic action. The novel similarities observed by structural comparison of the helix–turn–helix (HTH) motifs of the thionins, including ligatoxin B, and the HTH DNA-binding proteins, led us to propose the working hypothesis that thionins represent a new group of DNA-binding proteins. This working hypothesis could be useful in further dissecting the molecular mechanisms of thionin cytotoxicity and of thionin opposition to multidrug resistance, and useful in clarifying the physiological function of thionins in plants.

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Basic fibroblast growth factor regulates IGF-I binding proteins in the clonal osteoblastic cell line MC3T3-E1

Journal of Bone and Mineral Research ◽

10.1002/jbmr.5650100208 ◽

2009 ◽

Vol 10 (2) ◽

pp. 222-230 ◽

Cited By ~ 19

Author(s):

Marja M. Hurley ◽

Christine Abreu ◽

Yoshiyuki Hakeda

Keyword(s):

Growth Factor ◽

Fibroblast Growth Factor ◽

Cell Line ◽

Basic Fibroblast Growth Factor ◽

Binding Proteins ◽

Osteoblastic Cell ◽

Fibroblast Growth ◽

Osteoblastic Cell Line ◽

Igf I

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Built by association: structure and function of helix-loop-helix DNA-binding proteins

Structure ◽

10.1016/s0969-2126(00)00002-2 ◽

1994 ◽

Vol 2 (1) ◽

pp. 1-4 ◽

Cited By ~ 16

Author(s):

Simon EV Phillips

Keyword(s):

Dna Binding ◽

Binding Proteins ◽

Dna Binding Proteins ◽

Structure And Function ◽

Helix Loop Helix ◽

Association Structure ◽

And Function

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The Saccharomyces cerevisiae SIN3 gene, a negative regulator of HO, contains four paired amphipathic helix motifs

Molecular and Cellular Biology ◽

10.1128/mcb.10.11.5927-5936.1990 ◽

1990 ◽

Vol 10 (11) ◽

pp. 5927-5936

Author(s):

H Wang ◽

I Clark ◽

P R Nicholson ◽

I Herskowitz ◽

D J Stillman

Keyword(s):

Dna Binding ◽

Binding Proteins ◽

Sequence Data ◽

Gene Mutations ◽

Dna Binding Proteins ◽

Negative Regulator ◽

Amphipathic Helix ◽

Haploid Strain ◽

Ho Gene

The SIN3 gene (also known as SDI1) is a negative regulator of the yeast HO gene. Mutations in SIN3 suppress the requirement for the SWI5 activator for expression of the yeast HO gene and change the normal asymmetric pattern of HO expression in mother and daughter cells. Furthermore, the in vitro DNA-binding activity of several DNA-binding proteins is reduced in extracts prepared from sin3 mutants. We have cloned the SIN3 gene and determined that a haploid strain with a SIN3 gene disruption is viable. We determined the sequence of the SIN3 gene, which is predicted to encode a 175-kDa polypeptide with four paired amphipathic helix motifs. These motifs have been identified in the myc family of helix-loop-helix DNA-binding proteins and in the TPR family of regulatory proteins. The SIN3 transcript was mapped, and it was determined that the SIN3 transcript was absent in stationary-phase cells. Immunofluorescence microscopy with anti-SIN3 antibody demonstrated that SIN3 protein was present in nuclei. A comparison of restriction map and sequence data revealed that SIN3 is the same as regulatory genes UME4 and RPD1.

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