title: Re-evaluating the role of strongly charged sequences in amphipathic cell-penetrating peptides:    a fluorescence study using Pep-1.
abstract: Cell-penetrating peptides (CPPs) are able to translocate across biological membranes and deliver bioactive proteins. Cellular uptake and intracellular distribution of CPPs is commonly evaluated with fluorescent labels, which can alter peptide properties. The effect of carboxyfluorescein label in the Lys-rich domain of the amphipathic CPP pep-1, was evaluated and compared with non-labelled pep-1 in vitro and in vivo. A reduced membrane affinity and an endosomal-dependent translocation mechanism, at variance with non-labelled pep-1, were detected. Therefore, the charged domain is not a mere enabler of peptide adsorption but has a crucial role in the translocation pathway of non-labelled pep-1.
authors.affiliation: Centro de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, Ed. C8, Campo Grande, 1749-016 Lisboa, Portugal.
authors.forename: Sónia T
authors.initials: ST
authors.lastname: Henriques
authors.forename: Júlia
authors.initials: J
authors.lastname: Costa
authors.forename: Miguel A R B
authors.initials: MA
authors.lastname: Castanho
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D003543:Cysteamine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D005452:Fluoresceins / Q000737:chemistry / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000737:chemistry / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008564:Membrane Potentials; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D021381:Protein Transport; D012996:Solutions / Q000737:chemistry; D055672:Static Electricity
chemical_list: D005452:Fluoresceins; D005456:Fluorescent Dyes; C503924:Pep-1 peptide; D010455:Peptides; D012996:Solutions; C503925:pep-1CF peptide; D003543:Cysteamine