pmKate2-peroxi is a mammalian expression vector intended for far-red fluorescent labeling of peroxisomes in living cells. The vector encodes far-red fluorescent protein mKate2 (see reporter description) targeted to the matrix of peroxisomes by tripeptide SKL (peroxisomal targeting signal, PTS) fused to the mKate2 C-terminus.

Transiently transfected HeLa cells expressing mKate2 fusion with peroxisomal targeting signal.

Scale bar represents 10 μm. Image from Shcherbo et al., 2009.

mKate2 codon usage is optimized for high expression in mammalian cells (humanized) [Haas et al., 1996]. To increase mRNA translation efficiency, Kozak consensus translation initiation site is generated upstream of the mKate2 coding sequence [Kozak, 1987].

pmKate2-peroxi vector can be used as a source of mKate2-PTS hybrid sequence. The vector backbone contains unique restriction sites that permit its excision and further insertion into expression vector of choice.

Note: The plasmid DNA was isolated from dam+-methylated E. coli. Therefore some restriction sites are blocked by methylation. If you wish to digest the vector using such sites you will need to transform the vector into a dam- host and make fresh DNA.

The vector backbone contains immediate early promoter of cytomegalovirus (PCMV IE) for protein expression, SV40 origin for replication in mammalian cells expressing SV40 T-antigen, pUC origin of replication for propagation in E. coli, and f1 origin for single-stranded DNA production. SV40 polyadenylation signals (SV40 poly A) direct proper processing of the 3'-end of the reporter mRNA.

SV40 early promoter (PSV40) provides neomycin resistance gene (Neor) expression to select stably transfected eukaryotic cells using G418. Bacterial promoter (P) provides kanamycin resistance gene expression (Kanr) in E. coli. Kanr/Neor gene is linked with herpes simplex virus (HSV) thymidine kinase (TK) polyadenylation signals.


Expression in mammalian cells

pmKate2-peroxi vector can be transfected into mammalian cells by any known transfection method. CMV promoter provides strong, constitutive expression of the mKate2-PTS fusion in eukaryotic cells. If required, stable transformants can be selected using G418 [Gorman, 1985].


Propagation in E. coli

Suitable host strains for propagation in E. coli include DH5alpha, HB101, XL1-Blue, and other general purpose strains. Plasmid incompatibility group is pMB1/ColE1. The vector confers resistance to kanamycin (30 μg/ml) to E. coli hosts. Copy number in E. coli is about 500.