Inhibition of PrKX, a novel protein kinase, and the cyclic AMP-dependent protein kinase PKA by the regulatory proteins of adeno-associated virus type 2.

Adeno-associated virus encodes four nonstructural proteins, which are known as Rep78, Rep68, Rep52, and Rep40. Expression of these nonstructural proteins affects cell growth and gene expression through processes that have not yet been characterized. Using a yeast two-hybrid screen, we have demonstrated that a stable interaction occurs between the viral proteins Rep78 and Rep52 and the putative protein kinase PrKX, which is encoded on the X chromosome. The stability and specificity of the Rep-PrKX interaction were confirmed by coimmunoprecipitation of complexes assembled in vitro and in vivo. Overexpressed PrKX, which was purified from cos cells, was shown to phosphorylate a synthetic protein kinase A (PKA) substrate. However, this activity was dramatically inhibited by stoichiometric amounts of Rep52 and weakly inhibited with Rep68, which lacks the carboxy-terminal sequence contained in Rep52. Similarly, a stable interaction was observed with Rep78, which also contains the carboxy-terminal sequence of Rep52. A stable interaction and inhibition were also observed between Rep52 and the catalytic subunit of PKA. By using surface plasmon resonance and kinetic studies, Kis of approximately 300 and 167 nM were calculated for Rep52 with PKA and with PrKX, respectively. Thus, Rep52 but not Rep68 can significantly inhibit the trans- and autophosphorylation activities of these kinases. The biological effects of Rep78-specific inhibition of PKA-responsive genes are illustrated by the reduction of steady-state levels of cyclic AMP-responsive-element-binding protein and cyclin A protein.

Where have all the captains gone? A comparison of active and reserve MC ranks and ages, Vietnam to Desert Storm.

An analysis of ages and ranks of hospital-based physicians in one area of the Persian Gulf War was used for a comparison with similar data from the Vietnam War. Mean age in the latter was 33.4 years; rank was Captain (0-3.24). In Desert Storm, mean age and rank significantly increased to 46.0 years and close to Lieutenant Colonel (0-4.73), respectively. The large proportion of Reserve Component Physicians (75%) in the Persian Gulf War is the probable explanation for these findings. Medical Corps recruitment and retention problems may result from this most recent war and pose potential threats to success in future U.S. conflicts.