I ntracellular parasitism defines the most intimate of interactions between a pathogen and host. Inherent in this equation are the needs of the pathogen to enter the cell and establish a replication-permissive niche while neutralizing and subverting cellular defenses. The protozoan parasite Toxoplasma gondii is particularly adept at every stage of intracellular parasitism, which has contributed...

As a prominent regulator of plant growth and development, the hormone auxin plays an essential role in controlling cell division and expansion. Auxin-responsive gene transcription is mediated through the TRANSPORT INHIBITOR RESPONSE1/AUXIN SIGNALING F-BOX (TIR1/AFB) pathway. Roles for TIR1/AFB pathway components in auxin response are understood best, but additional factors implicated in auxin r...

Previous studies have demonstrated that both the 105,000 X g soluble supernatant (S105) and microsomal membranes from rat liver are required for the enzymatic conversion of squalene to cholesterol (Scallen, T.J., Dean, W.J., and Schuster, M.W. (1968) J. Biol. Chem. 243, 5202). It was postulated that S105 contained a noncatalytic carrier protein which was required for this enzymatic process (Sca...

Like many intracellular microbes, the protozoan parasite Toxoplasma gondii injects effector proteins into cells it invades. One group of these effector proteins is injected from specialized organelles called the rhoptries, which have previously been described to discharge their contents only during successful invasion of a host cell. In this report, using several reporter systems, we show that ...

The DEHYDRATION-RESPONSIVE ELEMENT BINDING PROTEIN2A (DREB2A) transcription factor controls water deficit-inducible gene expression and requires posttranslational modification for its activation. The activation mechanism is not well understood; however, the stability of this protein in the nucleus was recently found to be important for its activation. Here, we report the isolation of Arabidopsi...

Apicomplexan parasites invade host cells by forming a ring-like junction with the cell surface and actively sliding through the junction inside an intracellular vacuole. Apical membrane antigen 1 is conserved in apicomplexans and a long-standing malaria vaccine candidate. It is considered to have multiple important roles during host cell penetration, primarily in structuring the junction by int...