Tip60, originally isolated as an HIV-1-Tat interactive protein, contains an evolutionarily conserved domain with yeast silencing factors. We demonstrate here direct biochemical evidence that this domain of Tip60 has histone acetyltransferase activity. The purified recombinant effectively acetylates H2A, H3, and H4 but not H2B of core histone mixtures. This substrate specificity has not been observed among histone acetyltransferases analyzed to date. These results indicate that Tip60 is a histone acetyltransferase with a novel property, suggesting that Tip60 and its related factors may introduce a distinct alteration on chromatin.

Alcadeinα (Alcα) is an evolutionarily conserved type I membrane protein expressed in neurons. We show here that Alcα strongly associates with kinesin light chain ( K D≈4–8 × 10−9 M) through a novel tryptophan‐ and aspartic acid‐containing sequence. Alcα can induce kinesin‐1 association with vesicles and functions as a novel cargo in axonal anterograde transport. JNK‐interacting protein 1 (JIP1), an adaptor protein for kinesin‐1, perturbs the transport of Alcα, and the kinesin‐1 motor complex dissociates from Alcα‐containing vesicles in a JIP1 concentration‐dependent manner. Alcα‐containing vesicles were transported with a velocity different from that of amyloid β‐protein precursor (APP)‐containing vesicles, which are transported by the same kinesin‐1 motor. Alcα‐ and APP‐containing vesicles comprised mostly separate populations in axons in vivo . Interactions of Alcα with kinesin‐1 blocked transport of APP‐containing vesicles and increased β‐amyloid generation. Inappropriate interactions of Alc‐ and APP‐containing vesicles with kinesin‐1 may promote aberrant APP metabolism in Alzheimer's disease.

The TATA box-binding factor TFIID plays a primary role in the process of transcription initiation by RNA polymerase II and its regulation by various gene-specific factors. Here we employ a permuted binding site/gel retardation assay with recombinant yeast and human TFIID to show that this factor induces DNA bending around the TATA element. These results are consistent with the presence of G + C-rich sequence elements flanking the consensus TATA element and led to the recently confirmed suggestion that TFIID interacts with the TATA element via the minor groove. They also raise the possibility that TFIID-induced bending might facilitate promoter interactions of other general factors in the preinitiation complex or interactions between general transcription factors and regulatory factors bound at upstream sites.