Lipolysis drives expression of the constitutively active receptor GPR3 to induce adipose thermogenesis

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The chicken neural extracellular matrix molecule restrictin: similarity with EGF-, fibronectin type III-, and fibrinogen-like motifs.

Restrictin is a chick neural extracellular matrix protein implicated in neural cell attachment and found to be associated with the cell surface recognition protein F11. Here we show by cDNA cloning that restrictin is a large multidomain protein composed of 4 structural motifs. At the N-terminus restrictin contains a cysteine-rich segment of about 140 aa that might link restrictin monomers into oligomers. This region is followed by 4.5 epidermal growth factor-like repeats and then by 9 consecutive motifs that are similar to fibronectin type III motifs. At the C-terminus restriction is related to the beta and gamma chains of fibrinogen, including similarity to a calcium-binding segment. Restrictin shows substantial sequence similarity with tenascin (cytotactin) throughout the polypeptide, and like tenascin, it forms oligomeric structures, as revealed by electron microscopy of immunoaffinity-purified restriction. The cell attachment site of restrictin is mapped to the C-terminal region by antibody perturbation experiments.     

Rule-based spatial modeling with diffusing,geometrically constrained molecules

Background  

We suggest a new type of modeling approach for the coarse grained, particle-based spatial simulation of combinatorially complex chemical reaction systems. In our approach molecules possess a location in the reactor as well as an orientation and geometry, while the reactions are carried out according to a list of implicitly specified reaction rules. Because the reaction rules can contain patterns for molecules, a combinatorially complex or even infinitely sized reaction network can be defined.     

Single Lipid Extraction: The Anchoring Strength of Cholesterol in Liquid-Ordered and Liquid-Disordered Phases

Cholesterol is important for the formation of microdomains in supported lipid bilayers and is enriched in the liquid-ordered phase. To understand the interactions leading to this enrichment, we developed an AFM-based single-lipid-extraction (SLX) approach that enables us to determine the anchoring strength of cholesterol in the two phases of a phase-separated lipid membrane. As expected, the forces necessary for extracting a single cholesterol molecule from liquid-ordered phases are significantly higher than for extracting it from the liquid-disordered phases. Interestingly, application of the Bell model shows two energy barriers that correlate with the head and full length of the cholesterol molecule. The resulting lifetimes for complete extraction are 90 s and 11 s in the liquid-ordered and liquid-disordered phases, respectively. Molecular dynamics simulations of the very same experiment show similar force profiles and indicate that the stabilization of cholesterol in the liquid-ordered phase is mainly due to nonpolar contacts.