Karin Abarca-Heidemann

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The expression of antigen presenting MHC class I molecules can be enhanced through cytokines, e.g. upon infection with bacteria or viruses, either directly by enhancing class I gene transcription or by increasing the amounts of accessory proteins of the loading complex. Tapasin plays a significant role in the peptide loading of class I molecules. Here, we(More)
Regulator of K(+) conductance (RCK) domains control the activity of a variety of K(+) transporters and channels, including the human large conductance Ca(2+)-activated K(+) channel that is important for blood pressure regulation and control of neuronal firing, and MthK, a prokaryotic Ca(2+)-gated K(+) channel that has yielded structural insight toward(More)
Gating of large conductance Ca(2+)-activated K(+) channels (BK or maxi-K channels) is controlled by a Ca(2+)-sensor, formed by the channel cytoplasmic C-terminal domain, and a voltage sensor, formed by its S0-S4 transmembrane helices. Here we analyze structural properties of a portion of the BK channel voltage sensing domain, the S3-S4 linker, using(More)
MthK is a Ca(2+)-gated K(+) channel whose activity is inhibited by cytoplasmic H(+). To determine possible mechanisms underlying the channel's proton sensitivity and the relation between H(+) inhibition and Ca(2+)-dependent gating, we recorded current through MthK channels incorporated into planar lipid bilayers. Each bilayer recording was obtained at up to(More)
Rod photoreceptors contain three different glutamic acid-rich proteins (GARPs) that have been proposed to control the propagation of Ca(2+) from the site of its entry at the cyclic nucleotide-gated channel to the cytosol of the outer segment. We tested this hypothesis by measuring the binding of Ca(2+) to the following five constructs related to GARPs of(More)
RCK (regulator of conductance of potassium) domains form a family of ligand-binding domains found in many prokaryotic K+ channels and transport proteins. Although many RCK domains contain an apparent nucleotide binding motif, some are known instead to bind Ca2+, which can then facilitate channel opening. Here we report on the molecular architecture and(More)
The outer segment of vertebrate photoreceptors is a specialized compartment that hosts all the signaling components required for visual transduction. Specific to rod photoreceptors is an unusual set of three glutamic acid-rich proteins (GARPs) as follows: two soluble forms, GARP1 and GARP2, and the N-terminal cytoplasmic domain (GARP' part) of the B1(More)
As large, multimeric, integral membrane proteins, ion channels pose technical challenges to analysis by NMR spectroscopy. Here we present a strategy to overcome some of these technical hurdles, using a representative ion channel modulatory domain, the regulator of K(+) conductance (RCK) domain from a K(+) channel cloned from Thermoplasma volcanium. By(More)
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