Characterization of rat BLOS2/Ceap, a putative yeast She3 homolog, as interaction partner of apoptosis antagonizing transcription factor/Che-1.
AATF/Che-1 is a coactivator of several transcription factors, including steroid hormone receptors. In search of novel interaction partners of AATF, we identified BLOS2 (BLOC1S2, also termed Ceap) from a rat cDNA library. BLOS2 is extremely conserved with a high degree of homology to yeast She3p. The clone isolated represents a splice variant encoding a polypeptide of 168 residues. Rat BLOS2 mRNA is highly expressed in brain and testis and at lower levels in other tissues, but not in skeletal or smooth muscle. Expression as a tagged fusion protein revealed predominant cytoplasmic, but also nuclear localization. In the cytoplasm, BLOS2 fusion proteins exhibit diffuse, filamentous, or dotted distribution, with the latter partially co-localizing with recycling endosomes. In addition, BLOS2 localizes to centrosomes or the pericentrosomal region. Moreover, BLOS2 co-localizes with myosin V globular tail domains in vesicle-like structures. However, a direct interaction could not be demonstrated. In transactivation assays, BLOS2 enhanced transcription from androgen receptor and p53-responsive promoters. However, this enhancement correlated with accumulation of both androgen receptor and p53, suggesting that BLOS2 has a stabilizing effect on these transcription factors. We propose that BLOS2 functions as an adapter in processes such as protein and vesicle processing and transport, and perhaps transcription.
Felten
Andrea
A
Institute of Genetics, University of Bonn, Roemerstr. 164, D-53117 Bonn, Germany.
Leister
Peter
P
Burgdorf
Sven
S
Uhlmann
Lutz
L
Scheidtmann
Karl Heinz
KH
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D024701:Myosin Type V / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D009687:Nuclear Proteins; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry; D051381:Rats; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry; D017385:Sequence Homology; D013154:Spleen / Q000378:metabolism; D013737:Testis / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*
C523104:Aatf protein, rat; C506807:BLOC1S2 protein, rat; D002352:Carrier Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C471176:SHE3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D024701:Myosin Type V