Biology subjects

Rombach, J.

Publications and source records attributed to Rombach, J..

3 recordsLinked to original sources

bioRxiv2025

A proteome-wide screen for membrane-interactions in intrinsically disordered regions of transmembrane proteins reveals a role in disease

Transmembrane proteins mediate essential cellular processes including signaling, transport, and ion flux. Besides their well-characterized structured domains, most contain intrinsically disordered regions, whose biological roles remain poorly understood. Evidence suggests that the functions of intrinsically disordered regions are context-dependent, a trait particularly relevant when anchored to cellular membranes. In this study, we probed peptide arrays with fluorescent liposomes to generate a high-resolution, proteome-wide map of membrane-interaction sites within intrinsically disordered regions of human transmembrane proteins. Screening 4,000 proteins, we identified membrane-interaction sites in [~]60% of cases. Among these, [~]63% represent amphipathic helices, while [~]17% resemble cationic cell-penetrating peptides. We demonstrate that membrane-interaction motifs can influence subcellular localization and may contribute to both physiological and pathological processes. Our findings establish membrane association as a key functional aspect of intrinsically disordered regions and provide a valuable resource for discovering non-canonical regulatory mechanisms in transmembrane proteins. The resource is available at MemRIDRdb.

cell biology↗

bioRxiv2024

Membrane curvature association of amphipathic helix 8 drives constitutive GPCR endocytosis

Cellular signaling relies on the activity of transmembrane receptors and their presentation on the cellular surface. Their continuous insertion in the plasma membrane is balanced by constitutive and activity dependent internalization, which is orchestrated by adaptor proteins recognizing semi-specific motifs within the receptors intracellular regions. Here we describe a complementary and evolutionary conserved and refined trafficking mechanism for G-protein coupled receptors (GPCR). This mechanism relies on the insertion of their amphipathic helix 8 into the inner leaflet of lipid membranes, orthogonal to the transmembrane helices. These amphipathic helices dictate subcellular localization of the receptors and autonomously drive their endocytosis by cooperative assembly and association with areas of high membrane curvature. The strength of helix 8 membrane insertion propensity quantitatively predicts the rate of constitutive internalization of GPCRs. This discovery advances our understanding of membrane protein trafficking and highlights a new principle of receptor-lipid interactions that may have broader implications for cellular signaling and therapeutic targeting. One-Sentence SummaryReceptor proteins navigate cellular membranes by interacting with their curvature using an evolutionary conserved mechanism that relies on amphipathic helices and complements direct coupling to the endocytic protein machinery.

cell biology↗

bioRxiv2020

Coding variants identified in diabetic patients alter PICK1 BAR domain function in insulin granule biogenesis

Bin/amphiphysin/Rvs (BAR) domains are positively charged crescent-shaped modules that shape negatively charged curved lipid membranes during membrane remodeling processes. The BAR domain proteins ICA69, PICK1 and arfaptins have recently been demonstrated to coordinate the budding and formation of immature secretory granules (ISGs) at the trans-Golgi network. Here, we identify four coding variants in the PICK1 gene from a Danish whole-exome screening of diabetic patients, that all involve change of positively charged residues in the PICK1 BAR domain. All four coding variants failed to rescue the insulin content in INS-1E cells upon KD of endogenous PICK1. Moreover, two variants showed dominant negative properties. Interestingly, in vitro assays addressing the BAR domain function suggest that the coding variants compromised membrane binding capacity but increased capacity to cause fission of liposomes. Live confocal microscopy and super-resolution microscopy further revealed that PICK1 resides transiently on ISGs before egress via vesicular budding events. Interestingly, this egress of PICK1 was accelerated in the coding variants. We propose that PICK1 assists or complements the removal of excess membrane and generic membrane trafficking proteins, and possibly also insulin from ISGs during the maturation process and that the coding variants may cause premature budding possibly explaining their dominant negative function.

cell biology↗