Labeling of Cytoskeletal Proteins in Living Cells Using Biotin Ligase Carrying a Fluorescent Protein.

Labeling with fluorescent proteins is now widely exploited for elucidating the functions and roles of target proteins in living cells. Previously, we developed a protein labeling method by combining a fluorescent protein with a biotinylation reaction from archaeon Sulfolobus tokodaii. Biotinylation from S.

Site-specific labeling of proteins by using biotin protein ligase conjugated with fluorophores.

Biotin protein ligase (BPL) mediates the covalent attachment of biotin to a specific lysine residue of biotin carboxyl carrier protein (BCCP). This biotinylation in Sulfolobus tokodaii is unique in that BPL forms a tight complex with the product, biotinylated BCCP, and this property was exploited for fluorescent labeling of a membrane protein. Thus, the truncated form of BCCP (BCCPΔ100, 69 residues) was fused to either the N or C terminus of the bradykinin B2 receptor (B2R).