Anti-TAF8 monoclonal antibody Made to order

The crystal structure of trisodium octafluoridotantalate, Na3TaF8, has been redetermined using diffractometer data collected at 153 K, resulting in more accurate bond distances and angles than obtained from a previous structure determination based on film data. The structure is built from layers running along [101], which are formed by distorted [TaF8] antiprisms and [NaF6] rectangular bipyramids sharing edges and corners. The individual layers are separated by eight-coordinated Na ions. Two atoms in the asymmetric unit are in special positions: the Ta atom is on a twofold axis in Wyckoff position 4e and one of the Na ions lies on an inversion centre in Wyckoff site 4d.

TFIID, comprising the TATA box binding protein (TBP) and 13 TBP-associated factors (TAFs), plays a role in nucleation in the assembly of the RNA polymerase II preinitiation complexes on protein-encoding genes. TAFs are shared among other transcription regulatory complexes (e.g., SAGA, TBP-free TAF-containing complex [TFTC], STAGA, and PCAF/GCN5). Human TAF10, a subunit of both TFIID and TFTC, has three histone fold-containing interaction partners: TAF3, TAF8, and SPT7Like (SPT7L). In human cells, exogenously expressed TAF10 remains rather cytoplasmic and leptomycin B does not affect this localization. By using fluorescent fusion proteins, we show that TAF10 does not have an intrinsic nuclear localization signal (NLS) and needs one of its three interaction partners to be transported into the nucleus. When the NLS sequences of either TAF8 or SPT7L are mutated, TAF10 remains cytoplasmic, but a heterologous NLS can drive TAF10 into the nucleus. Experiments using fluorescence recovery after photobleaching show that TAF10 does not associate with any cytoplasmic partner but that once transported into the nucleus it binds to nuclear structures. TAF10 binding to importin P in vitro is dependent on the coexpression of either TAF8 or TAF3, but not SPT7L. The cytoplasmic-nuclear transport of TAF10 is naturally observed during the differentiation of adult male germ cells. Thus, here we describe a novel role of the three mammalian interacting partners in the nuclear localization of TAF10, and our data suggest that a complex network of regulated cytoplasmic associations may exist among these factors and that this network is important for the composition of different TFIID and TFTC-type complexes in the nucleus.