Chi chong Lu

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We have used capacitance measurements with a 1-microsecond voltage clamp technique to probe electrogenic ion-transporter interactions in giant excised membrane patches. The hydrophobic ion dipicrylamine was used to test model predictions for a simple charge-moving reaction. The voltage and frequency dependencies of the apparent dipicrylamine-induced(More)
We have developed an alternating access transport model that accounts well for GAT1 (GABA:Na+:Cl-) cotransport function in Xenopus oocyte membranes. To do so, many alternative models were fitted to a database on GAT1 function, and discrepancies were analyzed. The model assumes that GAT1 exists predominantly in two states, Ein and E(out). In the Ein state,(More)
To explain cotransport function, the "alternating access" model requires that conformational changes of the empty transporter allow substrates to bind alternatively on opposite membrane sides. To test this principle for the GAT1 (GABA:Na+:Cl-) cotransporter, we have analyzed how its charge-moving partial reactions depend on substrates on both membrane sides(More)
Neurotransmitter transporters are reported to mediate transmembrane ion movements that are poorly coupled to neurotransmitter transport and to exhibit complex "channel-like" behaviors that challenge the classical "alternating access" transport model. To test alternative models, and to develop an improved model for the Na+- and Cl--dependent(More)
Mammalian rod cyclic nucleotide gated (CNG) channels (i.e., alpha plus beta subunits) are strongly inhibited by phosphatidylinositol 4, 5-bisphosphate (PIP(2)) when they are expressed in Xenopus oocytes and studied in giant membrane patches. Cytoplasmic Mg-ATP inhibits CNG currents similarly, and monoclonal antibodies to PIP(2) reverse the effect and(More)
A series of acylated chitin derivatives was prepared by reacting chitin in a solution of trifluoroacetic anhydride and each of the cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl carboxylic acids. The degree of O-acyl substitution was in a range of 1.1-1.4 depending upon the nature of the cyclic acid added, as determined by FT-IR analysis. The(More)
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