B-cells become activated by ligands with varying valency and mode of presentation to the B-cell receptor (BCR). We previously demonstrated that clustering the immunoglobulin M (IgM) isotype of BCR with an artificial soluble cross-linker stabilized an ordered phase-like domain that enriched kinases and depleted phosphatases to promote receptor tyrosine phosphorylation. BCR is also activated by ligands presented at surfaces, and here we activate B-cells via supported bilayers of phosphatidylcholine lipids, a natural ligand for the IgM BCR expressed in the CH27 cells used. Using superresolution fluorescence localization microscopy, along with a quantitative cross-correlation analysis, we find that BRCs engaged with bilayers sort minimal peptide markers of liquid-ordered and liquid-disordered phases, indicating that ordered-domain stabilization is a general feature of BCR clustering. The phosphatase CD45 is more strongly excluded from bilayer-engaged BRCs than a transmembrane peptide, indicating that mechanisms other than domain partitioning contribute to its organization. Experimental observations are assembled into a minimal model of receptor activation that incorporates both ordered domains and direct phosphatase exclusion mechanisms to produce a more sensitive response.
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http://dx.doi.org/10.1091/mbc.E19-09-0507 | DOI Listing |
α-Synuclein (αSyn), an intrinsically disordered protein implicated in Parkinson's disease, is potentially thought to initiate aggregation through binding to cellular membranes. Previous studies have suggested that anionic membrane charge is necessary for this binding. However, these studies largely focus on unmodified αSyn, while nearly all αSyn in the body is N-terminally acetylated (NTA).
View Article and Find Full Text PDFJ Mol Biol
January 2025
Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA. Electronic address:
The mammalian cell cycle is coordinated by primarily four cyclin-dependent kinases (CDKs), which are activated by a family of cyclin proteins to phosphorylate diverse protein effectors of cell growth and division. A wealth of qualitative protein interaction studies have supported a model in which different CDKs have specific cognate cyclin partners. However, there have been few quantitative measurements of binding kinetics and affinity to support our understanding of CDK-cyclin preferences and the structural origins of those preferences.
View Article and Find Full Text PDFJ Phys Condens Matter
January 2025
Dep. Fisica, Universidade Federal de Minas Gerais, ICEX, Av. Antonio Carlos 6627, Belo Horizonte, MG, 31270-901, BRAZIL.
Nowadays, experimental research advances in condensed matter physics are deep-rooted in the development and manipulation of nanomaterials, making it essential to explore the fundamental properties of materials that are candidates for nanotechnology. In this work, we study the dependence of the molybdenum disulfide (MoS2) Raman modes on the sample temperature and on the excitation laser power. From the correlation between these two sets of measurements, we determine the planar thermal conductivity of MoSmonolayers, bilayers, trilayers, four layers, seven layers, and eight layers.
View Article and Find Full Text PDFLangmuir
January 2025
School of Chemical Engineering and Translational Nanobioscience Research Center, Sungkyunkwan University, Suwon 16419, Republic of Korea.
Alkylphospholipids are single-chain lipid amphiphiles that possess clinically relevant biological activities driven by membrane-destabilizing interactions. Subtle variations in alkylphospholipid structure can lead to significant differences in their biological effects, yet corresponding membrane interactions remain underexplored. Herein, we employed the quartz crystal microbalance-dissipation (QCM-D) technique to characterize the real-time membrane interactions of three alkylphospholipids-edelfosine, miltefosine, and perifosine-on supported lipid bilayers with varying cholesterol fractions.
View Article and Find Full Text PDFHeliyon
January 2025
Department of Food Science and Technology, College of Agriculture, Isfahan University of Technology, 84156-83111, Isfahan, Iran.
Packaging films based on natural biopolymers often suffer from inadequate barrier and mechanical properties. To address these challenges, multilayer films have emerged as potential solutions. In this study, we prepared bilayer films using bitter vetch seed protein (BVSP) and polylactic acid (PLA).
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