RP1-hK5 is a rabbit polyclonal antibody made to the serine proteinase kallikrein-5 (hK5).  The antibody is made to a synthetic peptide based on the Kallikrein loop area of human Kallikrein-5.  RP1-hK5 reacts with human Kallikrein-5, and does not react with the human kallikreins (hK1-15).  The antibody has been peptide-affinity purified, concentrated to 1.0 mg/ml, with the addition of 0.05% sodium azide as preservative and 50% glycerol as cryoprotectant.

Kallikrein-5, also known as KLK-Like 2 and human stratum corneum tryptic enzyme (HSCTE), is a trypsin-like serine proteinase. Kallikrein-5 was originally described from the skin as an enzyme involved in turnover of the stratum corneum, and later cloned from human EST libraries as a Kallikrein-like enzyme. The skin is known to contain trypsin-like and chymotrypsin-like proteinases of 32 kDa and 25 kDa respectively, and these were determined to be hK5 and hK7. Kallikrein-5 is found is greatest abundance in the skin, and also in the brain, with lesser signal in the kidney, lung, mammary gland, and testis. Human breast milk is reported to contain high levels of Kallikrein-5. Less stringent PCR detects hK5 in many tissues, and analysis of cell lines by Western blot shows that many cell lines make hK5.  Kallikrein-5 message is induced by estrogens in breast tumor cells, and hK5 has been reported to be elevated in ovarian cancer,  but down regulated in prostate tumors, and kallikrein-5 has been reported to be elevated is sera of ovarian cancer patients Different splice variants of hK5 have also been implicated as markers in ovarian cancer. A 269 amino acid form with a shorter carboxyterminus that lacks the catalytic serine has been reported, as well as a 253 amino acid form using a different start site and containing a deletion that removes the catalytic cysteine. Endogenous inhibitors include kallistatin, protein-C inhibitor and α1-proteinase inhibitor, although Kallikrein-5 can be found complexed to a number of different proteinase inhibitors. Pre-pro-kallikrein-5 has the 29 amino acid signal sequence that is removed before secretion, and the Pro-kallikrein-5 is activated to Kallikrein-5 by removal of the 37 amino acid propeptide domain. The full length hK5 sequence codes for a protein of 293 amino acids, with predicted mass of 32 kDa, and a very basic pI of 9.45, and the processed hK5 has an apparent mass of 32-34 kDa on reduced SDS PAGE gels.  A range of different sized bands can be seen for Kallikrein-5 in different tissues and in cell culture media, ranging from 16-32 kDa, and likely representing different proteolytically processed forms, but perhaps also the different splice variants. A recommended starting concentration for Western blots is 1:1,000 when using colorimetric substrates such as BCIP/NBT, and 1:5,000 for chemiluminescent substrates.  Higher concentrations of antibody may be needed for samples from more distantly related species.  

FOR RESEARCH USE ONLY. NOT FOR USE IN HUMANS.

The undiluted antibody solution is stable for 12 months at -20°C.

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