title: MCEF, the newest member of the AF4 family of transcription factors involved in leukemia, is a positive transcription elongation factor-b-associated protein.
abstract: Positive transcription elongation factor-b (P-TEFb) contains CDK9 and cyclin T(1). P-TEFb was affinity purified from a stably transfected cell line that expresses epitope-tagged CDK9, and proteins that appeared to be specifically bound were sequenced. In addition to CDK9, previously identified isoforms of cyclin T (including T(1), T(2A) and T(2B)), HSP90 and CDC37, this analysis identified a novel protein named MCEF. Cloning of its cognate cDNA revealed that MCEF is the newest member of the AF4 family of transcription factors involved in acute lymphoblastic leukemia. MCEF RNA was expressed in all human tissues examined, and antisera directed against recombinant MCEF specifically immunoprecipitated P-TEFb. Ectopic expression of MCEF did not activate HIV-1 replication, and tethering of MCEF to a promoter did not activate transcription.
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, N.Y., USA.
authors.forename: Mario Clemente
authors.initials: MC
authors.lastname: Estable
authors.forename: Mojgan H
authors.initials: MH
authors.lastname: Naghavi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kato
authors.forename: Hua
authors.initials: H
authors.lastname: Xiao
authors.forename: Jun
authors.initials: J
authors.lastname: Qin
authors.forename: Anders
authors.initials: A
authors.lastname: Vahlne
authors.forename: Robert G
authors.initials: RG
authors.lastname: Roeder
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D042863:Cyclin-Dependent Kinase 9; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D017930:Genes, Reporter; D015497:HIV-1 / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D007938:Leukemia / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D042925:Positive Transcriptional Elongation Factor B; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins; D016415:Sequence Alignment; D014018:Tissue Distribution; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D035602:Transcriptional Elongation Factors
chemical_list: C471348:AFF4 protein, human; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C481011:SUPT4H1 protein, human; C112224:SUPT5H protein, human; D014157:Transcription Factors; D035602:Transcriptional Elongation Factors; D042925:Positive Transcriptional Elongation Factor B; D017346:Protein Serine-Threonine Kinases; C467969:CDK9 protein, human; D042863:Cyclin-Dependent Kinase 9; D018844:Cyclin-Dependent Kinases