The TRK1 potassium transporter is the critical effector for killing of Candida albicans by the cationic protein, Histatin 5.

The principal feature of killing of Candida albicans and other pathogenic fungi by the catonic protein Histatin 5 (Hst 5) is loss of cytoplasmic small molecules and ions, including ATP and K(+), which can be blocked by the anion channel inhibitor 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid. We constructed C. albicans strains expressing one, two, or three copies of the TRK1 gene in order to investigate possible roles of Trk1p (the organism's principal K(+) transporter) in the actions of Hst 5.

Epitope tagging of the yeast K(+) carrier Trk2p demonstrates folding that is consistent with a channel-like structure.

TRK family proteins, which mediate the concentrative uptake of potassium by plant cells, fungi, and bacteria, resemble primitive potassium channels in sequence and have recently been proposed actually to fold like potassium channels in a 4-MPM motif (Durell, S. R., and Guy, H.

Ligand Binding Domains of human Vascular Endothelial Growth Factor Receptor.

Four cDNA clones, encoding truncated Flt-1 mutants consisting of loop 2, 1-2, 2-3 and 1-3, were amplified by PCR from human placenta cDNA library and the corresponding gene fragments were named Flt-1(2) Flt-1(1-2) Flt-1(2-3) and Flt-1(1-3). In order to detect which part of the extracellular domain was involved in ligand binding, the interaction between Flt-1 mutants and hVEGF(165) was studied with yeast two-hybrid system. The data presented here suggest that both Flt-1(2-3) and Flt-1(1-3) were able to bind hVEGF(165).

Expression, Purification and Biological Activity Analysis of Human Vascular Endothelial Growth Factor (VEGF(165)) in Pichia pastoris.

The human VEGF(165) cDNA was amplified by PCR, and was inserted, after confirming by DNA sequence analysis, into the Pichia pastoris expression vector pPIC9K containing AOX1 promoter and lead sequence of alpha factor gene to form a recombinant expression plasmids pPIC9K/hVEGF(165). This recombinant plasmid was transformed into KM71. Transformants were screened, cultured inflasks and induced by the addition of 1% methanol.