PubMed · 4619949
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
G Blobel. 1974. Ribosome-membrane interaction.. https://pubmed.ncbi.nlm.nih.gov/4619949/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
In a range of low ionic strength, aqueous dispersions of the anionic phospholipid DMPG (dimyristoylphosphatidylglycerol) have a transparent intermediate phase (IP, between T(m)(on) congruent with 20 degrees C and T(m)(off) congruent with 30 degrees C) between the turbid gel and fluid membrane phases, evidenced in turbidity data. Small angle x-ray scattering results on DMPG dispersions show that, besides the bilayer peak present in all phases, a peak corresponding to a mesoscopic structure at approximately 400 A is detected only in IP. The dependence of this peak position on DMPG concentration suggests a correlation in the bilayer plane, consistent with the stability of vesicles in IP. Moreover, observation of giant DMPG vesicles with phase contrast light microscopy show that vesicles "disappear" upon cooling below T(m)(off) and "reappear" after reheating. This further proves that although vesicles cannot be visualized in IP, their overall structure is maintained. We propose that the IP in the melting regime corresponds to unilamellar vesicles with perforations, a model which is consistent with all described experimental observations. Furthermore, the opening of pores across the membrane tuned by ionic strength, temperature, and lipid composition is likely to have biological relevance and could be used in applications for controlled release from nanocompartments.
We show that it is possible to produce phosphorylation difference maps of biological membranes under conditions which reflect those in vivo and in which proteins remain functional. We also demonstrate that absolute levels of phosphorylation are retrieved through the application of an appropriate calibration method. Finally we show that the kinetics of phosphorylation/dephosphorylation can also be monitored. These methods are demonstrated on photosynthetic membranes from higher plants, for which protein phosphorylation is the dominant regulatory mechanism. We show directly that the most recent estimates of the phosphorylation levels in this system are reasonably accurate. Phosphorylation difference maps show that the distribution of phosphates is not even, with significantly higher levels at the membrane margins and patches of high phosphate density next to patches of low charge density.
A mathematical description is presented of osmotic flows across both ideally semipermeable membranes and membranes permeable not only for the solvent but also for the solute. The principles of thermodynamics of irreversible processes used for the description are given and illustrated on the example of electroosmosis. Modern ideas about the physical basis of osmotic pressure on porous membranes are discussed and an experiment is described that models the processes of osmosis on a macroscopic level.