In studies of the minimum physiochemical requirements for lipid membrane formation, we have made liposomes from dilute, aqueous dispersions of C(8)-C(18) single-chain amphiphiles. In general, membrane formation from ionic soaps and detergents requires the presence of uncharged amphiphiles. Vesicles were characterized by phase-contrast microscopy, by trapping of ionic dyes, as well as by negativestain and freez-frature electron microscopy. They were typically heterogeneous in size, but the average diameter could be experimentally varied in some cases over the range of 1 to 100 micrometer. Uni-, oligo-, and multilamellar vesicles were observed. Membrane permeability to various solutes was determined in part by a new technique which utilized phase-contract microscopy; when impermeable vesciles exclude added solutes such as sucrose, refractive index differences are created between vesicle contents and surrounding medium, so that the vesicles appear bright in the phase microscope. Permeant solutes do not produce this effect. Spectrophotometric permeability determinations confirmed the results of this technique and provided quantitative measures of permeability. Monoalkyl liposomes have potential uses as models of biomembranes and in drug delivery. They are also relevant to the prebiotic origin of biomembranes.

Two peripheral proteins of the human eryth- The human erythrocyte membrane provides a model system for investigating protein-membrane associations at the molecular level. Of particular interest is the existence of an extensive cytoskeletal network that may control cell shape and deformability (1-3) and the distribution of intramembrane particles (4) and surface markers (5). Interactions between spectrin, the major cytoskeletal protein, and the cytoplasmic surface of the erythrocyte membrane have been studied in detail and partially characterized (6-10). Bennett and Branton (6) have demonstrated the existence of a class of sites to which spectrin binds with high affinity, and recent evidence (8,11,12) indicates that band 2

No abstract

Peptides corresponding to various regions of type I rat transforming growth factor (rTGF) have been chem-

No abstract