placental alkaline phosphatase placental alkaline phosphatase alkaline phosphatase, placental type also known as placental alkaline phosphatase (plap) is an allosteric enzyme that in humans is encoded by the alpp gene. alppavailable structurespdbortholog search: pdbe rcsb list of pdb id codes1ew2, 1zeb, 1zed, 1zef, 2glq, 3mk0, 3mk1, 3mk2identifiersaliasesalpp, alp, palp, plap, plap-1, alkaline phosphatase, placental, alpi, iapexternal idsomim: 171800 mgi: 1924018 homologene: 122414 genecards: alpp gene location (human)chr.chromosome 2 (human)band2q37.1start232,378,724 bpend232,382,889 bpgene location (mouse)chr.chromosome 1 (mouse)band1|1 c5start87,025,724 bpend87,029,328 bprna expression patternbgeehumanmouse (ortholog)top expressed inplacentaright uterine tubeupper lobe of left lungright lunglower lobe of lungcanal of the cervixmuscle tissueleft uterine tubesmooth muscle tissueoccipital lobetop expressed induodenumjejunumileumsexually immature organismstomachlarge intestinecolonmedial ganglionic eminencepaneth cellspermatidmore reference expression databiogpsmore reference expression datagene ontologymolecular 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 / quickgoorthologsspecieshumanmouseentrez25076768ensemblensg00000163283ensmusg00000079440uniprotp05187f8vpq6refseq (mrna)nm_001632nm_001081082refseq (protein)np_001623np_001074551location (ucsc)chr 2: 232.38 – 232.38 mbchr 1: 87.03 – 87.03 mbpubmed searchwikidataview/edit humanview/edit mouse 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. 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. clinical significance plap is a tumor marker, especially in seminoma and ovarian cancer (e.g., dysgerminoma). plap is reliable only in non-smokers, as smoking interferes with measurement of plap, since serum concentrations of plap are increased up to 10-fold in smokers and its measurement is therefore of little value in this group.