Transporters of the solute carrier superfamily (SLCs) are responsible for the transmembrane traffic of the majority of chemical substances in cells and tissues and are therefore of fundamental biological importance. As is often the case with membrane proteins that can be heavily glycosylated, a lack of reliable high-affinity binders hinders their functional analysis. Purifying and reconstituting transmembrane proteins in their lipidic environments remains challenging and standard approaches to generate binders for multi-transmembrane proteins, such as SLCs, channels or G protein-coupled receptors (GPCRs) are lacking.
View Article and Find Full Text PDFSolute carriers (SLCs) are membrane transporters that import and export a range of endogenous and exogenous substrates, including ions, nutrients, metabolites, neurotransmitters, and pharmaceuticals. Despite having emerged as attractive therapeutic targets and markers of disease, this group of proteins is still relatively underdrugged by current pharmaceuticals. Drug discovery projects for these transporters are impeded by limited structural, functional, and physiological knowledge, ultimately due to the difficulties in the expression and purification of this class of membrane-embedded proteins.
View Article and Find Full Text PDFThe SLC26 family of transporters maintains anion equilibria in all kingdoms of life. The family shares a 7 + 7 transmembrane segments inverted repeat architecture with the SLC4 and SLC23 families, but holds a regulatory STAS domain in addition. While the only experimental SLC26 structure is monomeric, SLC26 proteins form structural and functional dimers in the lipid membrane.
View Article and Find Full Text PDFThe SLC26 or SulP proteins constitute a large family of anion transporters that are ubiquitously expressed in pro- and eukaryotes. In human, SLC26 proteins perform important roles in ion homeostasis and malfunctioning of selected members is associated with diseases. This protocol details the production and crystallization of a prokaryotic SLC26 homolog, termed SLC26Dg, from .
View Article and Find Full Text PDFSolute carriers from the SLC4, SLC23, and SLC26 families are involved in pH regulation, vitamin C transport and ion homeostasis. While these families do not share any obvious sequence relationship, they are united by their unique and novel architecture. Each member of this structural class is organized into two structurally related halves of seven transmembrane segments each.
View Article and Find Full Text PDFThe SLC26 family of membrane proteins combines a variety of functions within a conserved molecular scaffold. Its members, besides coupled anion transporters and channels, include the motor protein Prestin, which confers electromotility to cochlear outer hair cells. To gain insight into the architecture of this protein family, we characterized the structure and function of SLC26Dg, a facilitator of proton-coupled fumarate symport, from the bacterium Deinococcus geothermalis.
View Article and Find Full Text PDFLight is an important environmental signal for all organisms on earth because it is essential for physiological signalling and the regulation of most biological systems. Halophiles found in salt-saturated ponds encode various archaeal rhodopsins and thereby harvest various wavelengths of light either for ion transportation or as sensory mediators. HR (halorhodopsin), one of the microbial rhodopsins, senses yellow light and transports chloride or other halides into the cytoplasm to maintain the osmotic balance during cell growth, and it exists almost ubiquitously in all known halobacteria.
View Article and Find Full Text PDFMicrobial rhodopsins, a diverse group of photoactive proteins found in Archaea, Bacteria, and Eukarya, function in photosensing and photoenergy harvesting and may have been present in the resource-limited early global environment. Four different physiological functions have been identified and characterized for nearly 5,000 retinal-binding photoreceptors, these being ion transporters that transport proton or chloride and sensory rhodopsins that mediate light-attractant and/or -repellent responses. The greatest number of rhodopsins previously observed in a single archaeon had been four.
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