Pappalysin-1, also known as
pregnancy-associated plasma protein A, and
insulin-like growth factor binding protein-4 protease is a
protein encoded by the
PAPPA gene in humans.
PAPPA is a secreted
protease whose main substrate is insulin-like growth factor binding proteins. Pappalysin-1 is also used in
for
Down syndrome.
Function
PAPPA encodes a secreted metalloproteinase which cleaves insulin-like growth factor binding proteins (IGFBPs). PAPPA's proteolytic function is activated upon
collagen binding. It is thought to be involved in local proliferative processes such as
wound healing and
bone remodeling. Low
Blood plasma level of this
protein has been suggested as a biochemical marker for
pregnancies with
aneuploid (fetuses with an abnormal number of
).
For example, low PAPPA may be commonly seen in prenatal screening for
Down syndrome.
Low levels may alternatively predict issues with the
placenta, resulting in adverse complications such as intrauterine growth restriction,
preeclampsia, placental abruption,
premature birth, or
fetal death.
This enzyme catalyses the following chemical reaction:
Cleavage of the Met135-Lys bond in insulin-like growth factor binding protein (IGFBP)-4, and the Ser143-Lys bond in IGFBP-5
This enzyme belongs to the peptidase family M43.
Interactions
Pappalysin-1 has been shown to interact with major basic protein.
Studies conducted at the Royal London Hospital in the United Kingdom, have shown that a marker of Down's syndrome may be expressed during the first trimester and second trimester of a pregnancy term. Concentrations of the Pregnancy-Associated Plasma Protein (PAPPA) gene as well as other markers can help screen for Down's syndrome in the beginning stages of a woman's gestational period.
