Like all members of the Toll-like receptor (TLR) family, TLR4 comprises of a large ectodomain (ECD) involved in ligand recognition at the cell-surface, and a cytosolic Toll/interleukin-1 receptor (TIR) signalling domain, linked by a lipid membrane-anchored transmembrane (TM) domain (TMD).
Wzz is an integral inner membrane protein involved in regulating the length of lipopolysaccharide O-antigen glycans and essential for the virulence of many Gram-negative pathogens. In all Wzz homologs, the large periplasmic domain is proposed to be anchored by two transmembrane helices, but no information is available for the transmembrane and cytosolic domains. Here we have studied purified oligomeric Wzz complexes using cryoelectron microscopy and resolved the transmembrane regions within a semi-continuous detergent micelle.
Hereditary porphyrias are caused by mutations in genes that encode haem biosynthetic enzymes with resultant buildup of cytotoxic metabolic porphyrin intermediates. A longstanding open question is why the same causal porphyria mutations exhibit widely variable penetrance and expressivity in different individuals. Here we show that severely affected porphyria patients harbour variant alleles in the ABCB6 gene, also known as Lan, which encodes an ATP-binding cassette (ABC) transporter. Plasma membrane ABCB6 exports a variety of disease-related porphyrins.
As part of the innate immune system, the Toll-like receptors (TLRs) represent key players in the first line of defense against invading foreign pathogens, and are also major targets for therapeutic immunomodulation. TLRs are type I transmembrane proteins composed of an ectodomain responsible for ligand binding, a single-pass transmembrane domain, and a cytoplasmic Toll/Interleukin-1 receptor (TIR) signaling domain.