Provided herein are genetically encoded voltage indicator (GEVI) variants (e.g., QuasArba, QuasArbb) of Archaerhodopsin 3 useful for applications, such as optical measurement of membrane potential. Described herein are also polynucleotides encoding the variants, nucleic acid constructs, vectors (e.g., expression vectors), cells comprising the polynucleotides, nucleic acid constructs, and vectors, and cells comprising the polypeptides; and methods of using the variants.

Provided herein are genetically encoded voltage indicator (GEVI) variants (e.g., QuasArba, QuasArbb) of Archaerhodopsin 3 useful for applications, such as optical measurement of membrane potential. Described herein are also polynucleotides encoding the variants, nucleic acid constructs, vectors (e.g., expression vectors), cells comprising the polynucleotides, nucleic acid constructs, and vectors, and cells comprising the polypeptides; and methods of using the variants.

Stimulation of target cells using light, e.g., in vivo or in vitro, is implemented using a variety of methods and devices. One example involves a vector for delivering a light-activated NpHR-based molecule comprising a nucleic acid sequence that codes for light-activated NpHR-based molecule and a promoter. Either a high expression of the molecule manifests a toxicity level that is less than about 75%, or the light-activated NpHR-based proteins are expressed using at least two NpHR-based molecular variants. Each of the variants characterized in being useful for expressing a light-activated NpHR-based molecule that responds to light by producing an inhibitory current to dissuade depolarization of the neuron. Other aspects and embodiments are directed to systems, methods, kits, compositions of matter and molecules for ion pumps or for controlling inhibitory currents in a cell (e.g., in in vivo and in vitro environments).

Stimulation of target cells using light, e.g., in vivo or in vitro, is implemented using a variety of methods and devices. One example involves a vector for delivering a light-activated NpHR-based molecule comprising a nucleic acid sequence that codes for light-activated NpHR-based molecule and a promoter. Either a high expression of the molecule manifests a toxicity level that is less than about 75%, or the light-activated NpHR-based proteins are expressed using at least two NpHR-based molecular variants. Each of the variants characterized in being useful for expressing a light-activated NpHR-based molecule that responds to light by producing an inhibitory current to dissuade depolarization of the neuron. Other aspects and embodiments are directed to systems, methods, kits, compositions of matter and molecules for ion pumps or for controlling inhibitory currents in a cell (e.g., in in vivo and in vitro environments).

A polypeptide with a predominantly hydrophobic sequence long enough to span a membrane lipid bilayer as a transmembrane helix (TM) and comprising one or more dissociable groups inserts across a membrane spontaneously in a pH-dependant fashion placing one terminus inside cell. The polypeptide conjugated with various functional moieties delivers and accumulates them at cell membrane with low extracellular pH. The functional moiety conjugated with polypeptide terminus placed inside cell are translocated through the cell membrane in cytosol. The peptide and its variants or non-peptide analogs can be used to deliver therapeutic, prophylactic, diagnostic, imaging, gene regulation, cell regulation, or immunologic agents to or inside of cells in vitro or in vivo in tissue at low extracellular pH.

A polypeptide with a predominantly hydrophobic sequence long enough to span a membrane lipid bilayer as a transmembrane helix (TM) and comprising one or more dissociable groups inserts across a membrane spontaneously in a pH-dependant fashion placing one terminus inside cell. The polypeptide conjugated with various functional moieties delivers and accumulates them at cell membrane with low extracellular pH. The functional moiety conjugated with polypeptide terminus placed inside cell are translocated through the cell membrane in cytosol. The peptide and its variants or non-peptide analogs can be used to deliver therapeutic, prophylactic, diagnostic, imaging, gene regulation, cell regulation, or immunologic agents to or inside of cells in vitro or in vivo in tissue at low extracellular pH.

A method of precipitating cell membrane fragments from a cell lysate is disclosed. The method comprises contacting the cell lysate with a hydrophobic chelator and a metal ion under conditions that allow precipitation of the cell membrane fragments. Kits for precipitating cell membrane fragments are also disclosed.

A method of precipitating cell membrane fragments from a cell lysate is disclosed. The method comprises contacting the cell lysate with a hydrophobic chelator and a metal ion under conditions that allow precipitation of the cell membrane fragments. Kits for precipitating cell membrane fragments are also disclosed.

The present invention provides an isolated nucleic acid molecule comprising, or consisting of, the nucleic acid sequence of SEQ ID NO:1, or of a nucleic acid sequence of at least 1400 bp having at least 80% identity to said sequence of SEQ ID NO:1, wherein said isolated nucleic acid molecule leads to the specific expression in mouse cortex of an exogenous gene in a particular population of CNR1-positive cells when a nucleic acid sequence coding for said exogenous gene is operatively linked to said isolated nucleic acid molecule, said particular population of CNR1-positive cells being characterized in that it also expresses EFHD1, ENPP6 and GJC2.

The present invention provides an isolated nucleic acid molecule comprising, or consisting of, the nucleic acid sequence of SEQ ID NO:1, or of a nucleic acid sequence of at least 1400 bp having at least 80% identity to said sequence of SEQ ID NO:1, wherein said isolated nucleic acid molecule leads to the specific expression in mouse cortex of an exogenous gene in a particular population of CNR1-positive cells when a nucleic acid sequence coding for said exogenous gene is operatively linked to said isolated nucleic acid molecule, said particular population of CNR1-positive cells being characterized in that it also expresses EFHD1, ENPP6 and GJC2.