title: Activity and expression of murine small Maf family protein MafK.
abstract: Transcription factor NF-E2 is believed to be crucial for the regulation of erythroid-specific gene transcription. The three small Maf family proteins (MafF, MafG, and MafK), which are closely related to c-Maf proto-oncoprotein, constitute half of NF-E2 activity by virtue of forming heterodimers with the large, tissue-restricted subunit of NF-E2 (p45). We isolated cDNA clones encoding the murine small Maf family protein MafK and characterized the structure, activity, and expression profile of MafK mRNA. Functional analyses demonstrate that MafK binds to consensus NF-E2 sites in the absence of p45 in vitro and represses transcription of NF-E2 site-dependent reporter genes in transient transfection assays, while p45 introduced into cells alone does not effectively bind to DNA and does not affect transcription. In the presence of p45, MafK confers site-specific DNA binding activity to p45, and p45 in turn mediates transcriptional activation with its amino-terminal proline-rich domain. mRNA for MafK is expressed in fractions enriched for hematopoietic stem cells as well as erythroid cells, suggesting that MafK plays an important regulatory role in hematopoiesis.
authors.affiliation: Department of Biochemistry, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Igarashi
authors.forename: K
authors.initials: K
authors.lastname: Itoh
authors.forename: H
authors.initials: H
authors.lastname: Motohashi
authors.forename: N
authors.initials: N
authors.lastname: Hayashi
authors.forename: Y
authors.initials: Y
authors.lastname: Matuzaki
authors.forename: H
authors.initials: H
authors.lastname: Nakauchi
authors.forename: M
authors.initials: M
authors.lastname: Nishizawa
authors.forename: M
authors.initials: M
authors.lastname: Yamamoto
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001853:Bone Marrow / Q000378:metabolism; D002645:Chickens; D003001:Cloning, Molecular; D017931:DNA Primers; D018076:DNA, Complementary / Q000302:isolation & purification; D004268:DNA-Binding Proteins / Q000378:metabolism; D005333:Fetus; D015870:Gene Expression; D005786:Gene Expression Regulation; D015723:Gene Library; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D007700:Kinetics; D016350:Leucine Zippers; D008099:Liver / Q000378:metabolism; D050985:MafK Transcription Factor; D051379:Mice; D008969:Molecular Sequence Data; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D050985:MafK Transcription Factor; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors