Kallikrein-5, formerly known as stratum corneum tryptic enzyme (SCTE), is a
serine protease
Serine proteases (or serine endopeptidases) are enzymes that cleave peptide bonds in proteins. Serine serves as the nucleophilic amino acid at the (enzyme's) active site.
They are found ubiquitously in both eukaryotes and prokaryotes. Serin ...
expressed in the
epidermis
The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and Subcutaneous tissue, hypodermis. The epidermal layer provides a barrier to infection from environmental pathogens and regulates the ...
. In humans it is encoded by the ''KLK5''
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
.
[
] This gene is one of the fifteen
kallikrein
Kallikreins are a subgroup of serine proteases, enzymes capable of cleaving peptide bonds in proteins. In humans, plasma kallikrein (encoded by ''KLKB1 gene'') has no known paralogue, while tissue kallikrein-related peptidases (''KLKs'') encode a f ...
subfamily members located in a cluster on chromosome 19. Its expression is up-regulated by
estrogen
Estrogen (also spelled oestrogen in British English; see spelling differences) is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three ...
s and
progestins. Alternative splicing results in multiple transcript variants encoding the same protein.
KLK5 has been suggested to regulate cell shedding (
desquamation
Desquamation, or peeling skin, is the shedding of dead cells from the outermost layer of skin.
The term is .
Physiologic desquamation
Keratinocytes are the predominant cells of the epidermis, the outermost layer of the skin. Living keratin ...
) in conjunction with
KLK7
Kallikrein-related peptidase 7 (KLK7) is a serine protease that in humans is encoded by the ''KLK7'' gene. KLK7 was initially purified from the epidermis and characterised as stratum corneum chymotryptic enzyme (SCCE). It was later identified as ...
and
KLK14, given its ability to degrade proteins which form the extracellular component of cell junctions in the
stratum corneum
The stratum corneum (Latin language, Latin for 'horny layer') is the outermost layer of the epidermis (skin), epidermis. Consisting of dead tissue, it protects underlying tissue from infection, dehydration, chemicals and mechanical stress. It is ...
. It is proposed that KLK5 regulates this process since it is able to self-activate in addition to activating KLK7 and KLK14.
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References
Further reading
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External links
* The
MEROPS
MEROPS is an online database for peptidases (also known as proteases, proteinases and proteolytic enzymes) and their inhibitors. The classification scheme for peptidases was published by Rawlings & Barrett in 1993, and that for protein inhibito ...
online database for peptidases and their inhibitors
S01.017
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