Alkaline phosphatase, placental type

Alkaline phosphatase, placental type also known as placental alkaline phosphatase (PLAP) is an allosteric enzyme that in humans is encoded by the ALPP gene.^[5][6][7]

ALPP
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 1EW2, 1ZEB, 1ZED, 1ZEF, 2GLQ, 3MK0, 3MK1, 3MK2
Identifiers
Aliases	ALPP, ALP, PALP, PLAP, PLAP-1, alkaline phosphatase, placental, ALPI, IAP
External IDs	OMIM: 171800; MGI: 1924018; HomoloGene: 122414; GeneCards: ALPP; OMA:ALPP - orthologs
Gene location (Human) Chr. Chromosome 2 (human)[1] Band 2q37.1 Start 232,378,724 bp[1] End 232,382,889 bp[1]
Gene location (Mouse) Chr. Chromosome 1 (mouse)[2] Band 1|1 C5 Start 87,025,724 bp[2] End 87,029,328 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in placenta testicle right uterine tube upper lobe of left lung right lung lower lobe of lung canal of the cervix ectocervix left ovary muscle tissue Top expressed in duodenum epithelium of small intestine jejunum ileum migratory enteric neural crest cell sexually immature organism stomach lumbar subsegment of spinal cord large intestine colon More reference expression data BioGPS More reference expression data
Gene ontology Molecular function alkaline phosphatase activity phosphatase activity zinc ion binding protein binding hydrolase activity catalytic activity magnesium ion binding metal ion binding Cellular component integral component of membrane anchored component of membrane cell surface membrane plasma membrane Biological process metabolism dephosphorylation Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 250 76768 Ensembl ENSG00000163283 ENSMUSG00000079440 UniProt P05187 F8VPQ6 RefSeq (mRNA) NM_001632 NM_001081082 RefSeq (protein) NP_001623 NP_001074551 Location (UCSC) Chr 2: 232.38 – 232.38 Mb Chr 1: 87.03 – 87.03 Mb PubMed search [3] [4]
Wikidata
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Gene

There are at least four distinct but related alkaline phosphatases: intestinal (ALPI), placental (this enzyme), placental-like (ALPPL2), and liver/bone/kidney (ALPL) (tissue-nonspecific). The first three are located together on chromosome 2, whereas the tissue-nonspecific form is located on chromosome 1. The coding sequence for this form of alkaline phosphatase is unique in that the 3' untranslated region contains multiple copies of an Alu family repeat. In addition, this gene is polymorphic and three common alleles (type 1, type 2, and type 3) for this form of alkaline phosphatase have been well-characterized.^[7]

Function

Alkaline phosphatase, placental type is a membrane-bound glycosylated dimeric enzyme, also referred to as the heat-stable form, that is expressed primarily in the placenta, although it is closely related to the intestinal form of the enzyme as well as to the placental-like form.^[7]

Clinical significance

PLAP is a tumor marker, especially in seminoma^[8][9][10] and ovarian cancer (e.g., dysgerminoma).^[11] PLAP is reliable only in non-smokers, as smoking interferes with measurement of PLAP,^[12] since serum concentrations of PLAP are increased up to 10-fold in smokers and its measurement is therefore of little value in this group.^[13]