We supply bacteria Rhodopsin, membrane protein Bacteriorhodopsin bacteriopsin, HsBR.

Our Cell-free protein has been Function verificated.

Introduction

Bacteriorhodopsin (BR) is a 7-transmembrane protein that acts as a light-driven proton pump in archaebacteria. Due to its covalently bound colored ligand, BR is widely used as a control membrane protein, for example for crystallization assays and biochemical/biophysical experiments.

Structure

Bacteriorhodopsin is an integral membrane protein usually found in two-dimensional crystalline patches known as "purple membrane", which can occupy up to nearly 50% of the surface area of the archaeal cell. The repeating element of the hexagonal lattice is composed of three identical protein chains, each rotated by 120 degrees relative to the others. Each chain has seven transmembrane alpha helices and contains one molecule of retinalburied deep within, the typical structure for retinylidene proteins.

Function

Bacteriorhodopsin belongs to the microbial rhodopsins. They have similarities to vertebrate rhodopsins, the pigments that sense light in the retina. Rhodopsins also contain retinal; however, the functions of rhodopsin and bacteriorhodopsin are different, and there is limited similarity in their amino acid sequences. Both rhodopsin and bacteriorhodopsin belong to the 7TM receptor family of proteins, but rhodopsin is a G protein-coupled receptor and bacteriorhodopsin is not.

The bacteriorhodopsin molecule is purple and is most efficient at absorbing green light (wavelength 500-650 nm, with the absorption maximum at 568 nm). Bacteriorhodopsin has a broad excitation spectrum. For a detection wavelength between 700 and 800 nm, it has an appreciable detected emission for excitation wavelengths between 470 nm and 650 nm (with a peak at 570 nm). When pumped at 633 nm, the emission spectrum has appreciable intensity between 650 nm and 850 nm.

Main proton transfers in the bacteriorhodopsin photocycle. Protonatable groups and bound water molecules important for transport activity are shown as stick representation and blue spheres, respectively (PDB ID: 1C3W). Numbers with arrows represent the sequence of proton transfer reactions, the corresponding transitions between the photointermediates are indicated in the inset. The TM helices are shown in the following colors: A, blue; B, teal; C, green; D, lime green; E, yellow; F, orange; G, red; and the chromophore is depicted as black sticks. ① Proton transfer from the RSBH⁺ to the primary proton acceptor Asp85; ② proton release to the extracellular medium from the proton-releasing complex; ③ reprotonation of the RSB from the primary proton donor Asp96; ④ reprotonation of Asp96 from the cytoplasmic medium; ⑤ proton transfer from Asp85 to the proton-releasing complex.

The above information is a quote from Chem Rev. 2014 Jan 8; 114(1): 126–163. Published online 2013 Dec 23. doi: 10.1021/cr4003769

Specification