On the Cover
The high-resolution x-ray crystal structure of ACK-1 reveals, as expected, the typical protein kinase fold: a bilobate structure consisting of a beta-sheet dominated N-terminal lobe and a larger mostly alpha-helical C-terminal lobe with the nucleotide binding region formed by the cleft between the two lobes. The tyrosine kinase inhibitor PD158780 fits well in the active site of ACK and forms a hydrogen bond with Ala 208 within the linker region thus providing mechanistic information in support of our in vitrostudies that find PD158780 strongly inhibits kinase activity. For details, see article by Nur-E-Kamal et al. on page 297.