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An enzyme that catalyzes the hydrolysis and synthesis of phosphoric acid esters and the transfer of phosphate groups from phosphoric acid to other compounds.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



any of the enzymes of the hydrolase class that catalyze the hydrolysis of phosphoric acid esters in animals, plants, and microorganisms. Phosphatases maintain the phosphate level necessary for various biochemical processes; it may be that they also transport phosphate to the cell.

Depending on the chemical nature of the substrate, phosphatases are divided into monophosphatases, for example, glucose 6-phosphatase, which hydrolyze monoesters of phosphoric acid, and diphosphatases, such as nucleases, which break down the diesters of phosphoric acid. Monophosphatases, in turn, are classified as either specific (interacting with only one substrate) or nonspecific (having a wide range of activity). Depending on the nature of the medium in which their maximum activity is observed, nonspecific monophosphatases are referred to as either alkaline (optimal activity at pH 8–10) or acid (pH 4–6). Alkaline phosphatases are found in animal tissue (intestinal mucosa, placenta, kidneys, bones) and in milk, bacteria, and fungi; acid phosphatases are present in the tissue of the prostate gland, spleen, and liver and in yeasts, bacteria, and higher plants.

The most comprehensive studies have been carried out on the structure and mechanism of activity of the alkaline phosphatase in Escherichia coli. The enzyme is composed of two identical sub-units that function alternately; it contains firmly bonded Zn atoms and has a molecular weight of 80,000. The arrangement of the polypeptide chains is known, and it has been established that the reaction with the substrate passes through a stage of enzyme phosphorylation. A determination of the activity of acid and alkaline phosphatases is important in diagnosing diseases, such as rickets, that are accompanied by an increase in phosphatase activity.


The Enzymes, 3rd ed., vol. 4. New York-London, 1971.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Caption: Figure 6: Testicular seminoma (PLAP IHC stain, magnification x40).
It is from the principles of assimilation, accommodation and equilibration put forward by Piaget that PLAP comes into being.
(A): curvas de fluidez del PEBD y del PEm sin funcionalizar, y espectros FTIR de la fase PLA (B): mezclas sin carga, a: PLAp, b: PLA/PEBD1 y c: PLA/PEBD2, y (C): mezclas con carga, a: PLAp, b: PLAm/PEBD1 y c: PLAm/PEBD2.
(a) The seminoma cells (top) stained positively for (a) CD117 and (b) PLAP, while the Leydig cell tumor (bottom) was negative for both markers.
[1] Embryonal carcinoma is negative for D2-40 and positive for cytokeratin, SALL-4 and PLAP.
The main differential diagnoses of a malignant epithelial tumor in the mediastinum include primary thymic carcinoma (AE1/AE3 and CD117 positive), thyroid carcinoma (TTF1 positive), germ cell tumors (PLAP and CD117 positive), neuroendocrine tumors (NSE and Chromogranin A positive), mesothelioma (Calretinin and WT1 positive), and lymphoma (CD45 positive, although unlikely with this morphology).
(10,58,90) In the villous, cytotrophoblasts abruptly differentiate to syncytiotrophoblasts, which are typically strongly reactive with hCG and inhibin and to a lesser extent with hPL and placental alkaline phosphatase (PLAP).
Immunohistochemistry revealed tumour cells diffusely positive for CK AE1/AE3 (pancytokeratin) and focally positive for PLAP (Placental Alkaline Phosphatase) (Figure-2) and EMA (Epithelial Membrane Antigen).
Immunohistochemical studies were performed which exhibited immune-positivity for CD 117 / PLAP for seminoma and OCT 3 / 4 [Fig.
SALL4, OCT4, and LIN28.--SALL4.--A generation of novel germ cell markers, such as SALL4, OCT4, LIN28, NANOG homeobox (NANOG), and SOX2, have been described in the literature in recent years and have proven to be highly sensitive and specific for the differential diagnosis of germ cell tumors when compared with the more traditional germ cell markers, such as placental alkaline phosphatase (PLAP), [alpha]-fetoprotein (AFP), CD30, podoplanin (D2-40), CD117, and glypican-3.
2a), vimentin, smooth muscle actin, protein S-100 and CD99 and negative for placental-like-alkaline-phosphatase (PLAP) and CD117, which are two markers of germ cell tumours (Fig.
The germ cell tumor control block containing seminoma, embryonal carcinoma, yolk sac tumor, and placental tissues covers the most frequently used germ cell tumor markers, including sal-like protein 4 (SALL4), octamer-binding transcription factor 4 (OCT4), placental alkaline phosphatase (PLAP), sex-determining region Y box 2 (SOX2), NANOG homeobox (NANOG), cluster of differentiation (CD) 30, [alpha]-fetoprotein (AFP), glypican-3, CD117, podoplanin (D2-40), and cytokeratin (CK).