One-third of eukaryotic proteins are integrated within membranes, as are the targets of 40% of approved drugs. However, the lack of a general means of solubilizing, stabilizing and structurally characterizing active membrane proteins has frustrated efforts to understand their mechanisms and exploit their potential value. Here we report that bilayer disks formed by phospholipids and styrene maleic anhydride copolymer preserve the functional and structural integrity of alpha-helical and beta-barrel transmembrane proteins. They form 11 nm particles that are monodispersed, biocompatible, thermostable, and water-soluble, allowing diverse membrane proteins to be simply and rapidly presented for virtually any in vitro analysis.

Membrane sorting between secretory and endocytic organelles is predominantly controlled by small carrier vesicles or tubules that have specific protein coats on their cytoplasmic surfaces. Clathrin-clathrin-adaptor coats function in many steps of intracellular transport and are the most extensively studied of all transport-vesicle coats. In recent years, the determination of structures of clathrin assemblies by electron microscopy, of domains of clathrin and of its adaptors has improved our understanding of the molecular mechanisms of clathrin-coated-vesicle assembly and disassembly.

The NuRD complex is a multi-protein transcriptional corepressor that couples histone deacetylase and ATP-dependent chromatin remodelling activities. The complex regulates the higher-order structure of chromatin, and has important roles in the regulation of gene expression, DNA damage repair and cell differentiation. HDACs 1 and 2 are recruited by the MTA1 corepressor to form the catalytic core of the complex. The histone chaperone protein RBBP4, has previously been shown to bind to the carboxy-terminal tail of MTA1. We show that MTA1 recruits a second copy of RBBP4. The crystal structure reveals an extensive interface between MTA1 and RBBP4. An EM structure, supported by SAXS and crosslinking, reveals the architecture of the dimeric HDAC1:MTA1:RBBP4 assembly which forms the core of the NuRD complex. We find evidence that in this complex RBBP4 mediates interaction with histone H3 tails, but not histone H4, suggesting a mechanism for recruitment of the NuRD complex to chromatin.DOI: http://dx.doi.org/10.7554/eLife.13941.001