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PubMed2006

Conformation-assisted inhibition of protein-tyrosine phosphatase-1B elicits inhibitor selectivity over T-cell protein-tyrosine phosphatase.

PTP-1B represents an attractive target for the treatment of type 2 diabetes and obesity. Given the role that protein phosphatases play in the regulation of many biologically relevant processes, inhibitors against PTP-1B must be not only potent, but also selective. It has been extremely difficult to synthesize inhibitors that are selective over the highly homologous TCPTP. We have successfully exploited the conservative Leu119 to Val substitution between the two enzymes to synthesize a PTP-1B inhibitor that is an order of magnitude more selective over TCPTP. Structural analyses of PTP-1B/inhibitor complexes show a conformation-assisted inhibition mechanism as the basis for selectivity. Such an inhibitory mechanism may be applicable to other homologous enzymes.

Binding Sites↗
PubMed2000

Cellular mechanisms regulating protein phosphatase-1. A key functional interaction between inhibitor-2 and the type 1 protein phosphatase catalytic subunit.

Inhibitor-1 (I-1) and inhibitor-2 (I-2) selectively inhibit type 1 protein serine/threonine phosphatases (PP1). To define the molecular basis for PP1 inhibition by I-1 and I-2 charged-to-alanine substitutions in the Saccharomyces cerevisiae, PP1 catalytic subunit (GLC7), were analyzed. Two PP1 mutants, E53A/E55A and K165A/E166A/K167A, showed reduced sensitivity to I-2 when compared with wild-type PP1. Both mutants were effectively inhibited by I-1. Two-hybrid analysis and coprecipitation or pull-down assays established that wild-type and mutant PP1 catalytic subunits bound I-2 in an identical manner and suggested a role for the mutated amino acids in enzyme inhibition. Inhibition of wild-type and mutant PP1 enzymes by full-length I-2(1-204), I-2(1-114), and I-2(36-204) indicated that the mutant enzymes were impaired in their interaction with the N-terminal 35 amino acids of I-2. Site-directed mutagenesis of amino acids near the N terminus of I-2 and competition for PP1 binding by a synthetic peptide encompassing an I-2 N-terminal sequence suggested that a PP1 domain composed of amino acids Glu-53, Glu-55, Asp-165, Glu-166, and Lys-167 interacts with the N terminus of I-2. This defined a novel regulatory interaction between I-2 and PP1 that determines I-2 potency and perhaps selectivity as a PP1 inhibitor.

Amino Acid Sequence↗
PubMed2003

The protein tyrosine phosphatase Pez is a major phosphatase of adherens junctions and dephosphorylates beta-catenin.

Cell-cell adhesion regulates processes important in embryonal development, normal physiology, and cancer progression. It is regulated by various mechanisms including tyrosine phosphorylation. We have previously shown that the protein tyrosine phosphatase Pez is concentrated at intercellular junctions in confluent, quiescent monolayers but is nuclear in cells lacking cell-cell contacts. We show here with an epithelial cell model that Pez localizes to the adherens junctions in confluent monolayers. A truncation mutant lacking the catalytic domain acts as a dominant negative mutant to upregulate tyrosine phosphorylation at adherens junctions. We identified beta-catenin, a component of adherens junctions, as a substrate of Pez by a "substrate trapping" approach and by in vitro dephosphorylation with recombinant Pez. Consistent with this, ectopic expression of the dominant negative mutant caused an increase in tyrosine phosphorylation of beta-catenin, demonstrating that Pez regulates the level of tyrosine phosphorylation of adherens junction proteins, including beta-catenin. Increased tyrosine phosphorylation of adherens junction proteins has been shown to decrease cell-cell adhesion, promoting cell migration as a result. Accordingly, the dominant negative Pez mutant enhanced cell motility in an in vitro "wound" assay. This suggests that Pez is also a regulator of cell motility, most likely through its action on cell-cell adhesion.

Adherens Junctions↗
PubMed1982

Purification of gizzard myosin light-chain phosphatase, and reversible changes in the ATPase and superprecipitation activities of actomyosin in the presence of purified preparation of myosin light-chain phosphatase and kinase.

Sepharose 4B conjugated with phosphorylated myosin light chains was used in affinity chromatography of a partially purified preparation of gizzard myosin light-chain phosphatase (MLCP) (Onishi et al. (1979) J. Biochem. 86, 1283-1290). The MLCP preparation thus purified contained, according to SDS gel electrophoresis, three components of 67,000 (67 K), 54,000 (54 K), 34,000 (34 K) daltons. In an accompanying report, Uchiwa et al. (J. Biochem. 91, 273-282 (1982)) described the purification of gizzard myosin light-chain kinase, which consisted of two subunits; 130 K and 17 K daltons. Using the purified preparations of MLCP and MLCK, it was demonstrated a) that reversible changes in the ATPase and superprecipitation activities occur as myosin light chains are enzymatically phosphorylated and dephosphorylated, and b) that addition of a very low concentration of Ca2+ and its removal cause reversible changes in the turbidity of actomyosin suspensions as well as in the state of phosphorylation of myosin light chains only when MLCK and MLCP are both present. These results provide strong support for the proposal (see Ikebe et al. (1977) J. Biochem. 80, 299-302) that MLCK and MLCP play a key role in the Ca2+ regulation in gizzard.

Actomyosin↗
PubMed2006

The crystal structure of human receptor protein tyrosine phosphatase kappa phosphatase domain 1.

The receptor-type protein tyrosine phosphatases (RPTPs) are integral membrane proteins composed of extracellular adhesion molecule-like domains, a single transmembrane domain, and a cytoplasmic domain. The cytoplasmic domain consists of tandem PTP domains, of which the D1 domain is enzymatically active. RPTPkappa is a member of the R2A/IIb subfamily of RPTPs along with RPTPmu, RPTPrho, and RPTPlambda. Here, we have determined the crystal structure of catalytically active, monomeric D1 domain of RPTPkappa at 1.9 A. Structural comparison with other PTP family members indicates an overall classical PTP architecture of twisted mixed beta-sheets flanked by alpha-helices, in which the catalytically important WPD loop is in an unhindered open conformation. Though the residues forming the dimeric interface in the RPTPmu structure are all conserved, they are not involved in the protein-protein interaction in RPTPkappa. The N-terminal beta-strand, formed by betax association with betay, is conserved only in RPTPs but not in cytosolic PTPs, and this feature is conserved in the RPTPkappa structure forming a beta-strand. Analytical ultracentrifugation studies show that the presence of reducing agents and higher ionic strength are necessary to maintain RPTPkappa as a monomer. In this family the crystal structure of catalytically active RPTPmu D1 was solved as a dimer, but the dimerization was proposed to be a consequence of crystallization since the protein was monomeric in solution. In agreement, we show that RPTPkappa is monomeric in solution and crystal structure.

Amino Acid Sequence↗
PubMed2007

The MyD116 African swine fever virus homologue interacts with the catalytic subunit of protein phosphatase 1 and activates its phosphatase activity.

The DP71L protein of African swine fever virus (ASFV) shares sequence similarity with the herpes simplex virus ICP34.5 protein over a C-terminal domain. We showed that the catalytic subunit of protein phosphatase 1 (PP1) interacts specifically with the ASFV DP71L protein in a yeast two-hybrid screen. The chimeric full-length DP71L protein, from ASFV strain Badajoz 71 (BA71V), fused to glutathione S-transferase (DP71L-GST) was expressed in Escherichia coli and shown to bind specifically to the PP1-alpha catalytic subunit expressed as a histidine fusion protein (6xHis-PP1alpha) in E. coli. The functional effects of this interaction were investigated by measuring the levels of PP1 and PP2A in ASFV-infected Vero cells. This showed that infection with wild-type ASFV strain BA71V activated PP1 between two- and threefold over that of mock-infected cells. This activation did not occur in cells infected with the BA71V isolate in which the DP71L gene had been deleted, suggesting that expression of DP71L leads to PP1 activation. In contrast, no effect was observed on the activity of PP2A following ASFV infection. We showed that infection of cells with wild-type BA71V virus resulted in decreased phosphorylation of the alpha subunit of eukaryotic initiation factor 2 (eIF-2alpha). ICP34.5 recruits PP1 to dephosphorylate the alpha subunit of eukaryotic translational initiation factor 2 (also known as eIF-2alpha); possibly the ASFV DP71L protein has a similar function.

African Swine Fever Virus↗
PubMed2007

T-cell protein tyrosine phosphatase, distinctively expressed in activated-B-cell-like diffuse large B-cell lymphomas, is the nuclear phosphatase of STAT6.

Diffuse large B-cell lymphomas (DLBCLs) consist of clinically distinct subtypes: germinal center B-cell (GCB)-like and activated-B-cell (ABC)-like tumors, characterized by long and short survival, respectively. We reported distinct interleukin 4 (IL-4) responsiveness and STAT6 signaling in these DLBCL subtypes. Increased nuclear dephosphorylation of phospho-STAT6 (pSTAT6) was observed in ABC-like tumors, which exhibited a different expression profile of protein tyrosine phosphatases (PTPs). Among the differentially expressed PTPs, only T-cell PTP (TCPTP) localizes to the nucleus. Herein, we report that the elevated expression of TCPTP in ABC- versus GCB-like DLBCL tumors is not due to the distinct ontogeny of these neoplasms but rather may be an acquired feature of the tumors. Moreover, we report that STAT6 may serve as a physiological nuclear substrate for TCPTP. We demonstrate interactions between endogenous TCPTP and STAT6 and delineate the domains responsible for the interaction. Overexpression of TCPTP ameliorates IL-4-induced STAT6 phosphorylation and associated gene transcription, whereas knockdown of endogenous TCPTP results in increased IL-4-induced STAT6 signaling. Moreover, we report that TCPTP protein levels may be increased in response to IL-4 and that TCPTP may serve in a negative feedback loop for the suppression of IL-4-induced signaling. Taken together, these results identify TCPTP as a physiological regulator of STAT6 phosphorylation and suggest that specific increases in TCPTP expression in ABC-like DLBCLs may contribute to the different biological characteristics of these tumors.

Catalytic Domain↗
PubMed2003

Functions of the ectodomain and cytoplasmic tyrosine phosphatase domains of receptor protein tyrosine phosphatase Dlar in vivo.

The receptor protein tyrosine phosphatase (PTPase) Dlar has an ectodomain consisting of three immunoglobulin (Ig)-like domains and nine fibronectin type III (FnIII) repeats and a cytoplasmic domain consisting of two PTPase domains, membrane-proximal PTP-D1 and C-terminal PTP-D2. A series of mutant Dlar transgenes were introduced into the Drosophila genome via P-element transformation and were then assayed for their capacity to rescue phenotypes caused by homozygous loss-of-function genotypes. The Ig-like domains, but not the FnIII domains, are essential for survival. Conversely, the FnIII domains, but not the Ig-like domains, are required during oogenesis, suggesting that different domains of the Dlar ectodomain are involved in distinct functions during Drosophila development. All detectable PTPase activity maps to PTP-D1 in vitro. The catalytically inactive mutants of Dlar were able to rescue Dlar(-/-) lethality nearly as efficiently as wild-type Dlar transgenes, while this ability was impaired in the PTP-D2 deletion mutants DlarDeltaPTP-D2 and Dlar(bypass). Dlar-C1929S, in which PTP-D2 has been inactivated, increases the frequency of bypass phenotype observed in Dlar(-/-) genotypes, but only if PTP-D1 is catalytically active in the transgene. These results indicate multiple roles for PTP-D2, perhaps by acting as a docking domain for downstream elements and as a regulator of PTP-D1.

Amino Acid Sequence↗
PubMed2005

Insulin receptor kinase-associated phosphotyrosine phosphatases in hepatic endosomes: assessing the role of phosphotyrosine phosphatase-1B.

Previous work has shown that bisperoxo(1,10-phenanthroline)-oxovanadate(v) anion [bpV(phen)] induces potent insulin-mimicking effects in the rat, selectively activates the endosomal (EN) insulin receptor kinase (IRK) in liver, and markedly abolishes endosomal IRK-associated phosphotyrosine phosphatase (PTP) activity while reducing that of total ENs by approximately 30%. In this study we examined the relatively selective effect of bpv(phen) on endosomal PTP activities for the purpose of defining IRK-associated PTP(s). Using an in-gel PTP assay, we detected multiple (approximately 20) species of endosomal PTP (30 to >220 kDa), with five that were markedly inhibited after in vivo bpV(phen) administration. Using a combination of Mono Q anionic exchange chromatography and immunoblotting, we demonstrated that LAR (leukocyte common antigen-related), PTP-alpha, and PTP-1B were present in endosomal subfractions not significantly inhibited by bpv(phen). PTP-1B activity was assayed in immunoprecipitates from hepatic ENs of control and bpV(phen)-treated rats and was found to be inhibited by approximately 30% after bpv(phen) treatment. To clarify the role of PTP-1B in dephosphorylating IRK, we prepared hepatic ENs from wild-type and PTP-1B-null mice. We found that the phosphotyrosine content of IRK was similar in these two types of ENs, and that IRK dephosphorylation was not affected in ENs from PTP-1B-null mice compared with that in ENs from wild-type mice. These data suggest that LAR , PTP-alpha, and PTP-1B are not candidates for the IRK-associated PTP in hepatic ENs, and that IRK dephosphorylation in ENs may result from the concerted actions of several PTPs.

Animals↗
PubMed1992

Insulin receptor protein-tyrosine phosphatases. Leukocyte common antigen-related phosphatase rapidly deactivates the insulin receptor kinase by preferential dephosphorylation of the receptor regulatory domain.

A number of protein-tyrosine phosphatase(s) (PTPases) have been shown to dephosphorylate the insulin receptor in vitro; however, it is not known whether any individual PTPase has specificity for certain phosphotyrosine residues of the receptor that regulate its intrinsic tyrosine kinase activity. We evaluated the deactivation of the insulin receptor kinase by three candidate enzymes that are expressed in insulin-sensitive rat tissues, including the receptor-like PTPases LAR and LRP, and the intracellular enzyme, PTPase1B. Purified insulin receptors were activated by insulin and receptor dephosphorylation, and kinase activity was quantitated after incubation with recombinant PTPases from an Escherichia coli expression system. When related to the level of overall receptor dephosphorylation, LAR deactivated the receptor kinase 3.1 and 2.1 times more rapidly than either PTPase1B or LRP, respectively (p less than 0.03). To assess whether these effects were associated with preferential dephosphorylation of the regulatory (Tyr-1150) domain of the receptor beta-subunit, we performed tryptic mapping of the insulin receptor beta-subunit after dephosphorylation by PTPases. Relative to the rate of initial loss of 32P from receptor C-terminal sites, LAR dephosphorylated the Tris-phosphorylated Tyr-1150 domain 3.5 and 3.7 times more rapidly than either PTPase1B or LRP, respectively (p less than 0.01). The accelerated deactivation of the insulin receptor kinase by LAR and its relative preference for regulatory phosphotyrosine residues further support a potential role for this transmembrane PTPase in the physiological regulation of insulin receptors in intact cells.

Animals↗
PubMed2004

[Allele polymorphism of alkaline phosphatase, acid soluble phosphatase, and vitamin D-binding protein genes in postmenopausal osteoporosis].

AIM: To study polymorphism of genes involved in mechanisms regulating metabolism of bone tissue: alkaline (ALPL) and acid (ACP1) phosphatases, vitamin D-binding protein (GC); to ascertain associations of their genotypes and alleles with osteoporosis (OP) and mineral density of spinal and femoral bone tissue (BTMD). MATERIAL AND METHODS: Relevant genetic examination was made in 70 females with OP diagnosed by the WHO criteria (1994) aged 60-79 years (mean age 71.0 +/- 6.2 years) and 51 OP-free females in the same age interval (mean age 69.0 +/- 5.6 years). Polymorphic sites of the genes were examined by polymerase chain reaction. Trinucleotide repeat, ARG105GLN polymorphism of restrictive fragment length (PRFL), [GC, TRH420LYS] PRFL were studied for ALPL gene, ACP1 gene and GC gene, respectively. RESULTS: Association was found between frequencies of genotypes SS, 2F and FS, F allele of GC gene with OP as well as between PRFL of the spine, femur and some GC genotypes in OP women. Genes ALPL and ACP1 were not associated with OP. CONCLUSION: It is suggested that genotypes SS, 2F and FS have marked functional differences in fixation and transport of vitamin D active metabolites involved in metabolism of bone tissue in OP.

Absorptiometry, Photon↗
PubMedDate not supplied

Isoenzymes of lactate dehydrogenase, acid phosphatase, alkaline phosphatase and peroxidase in monkey kidney cell cultures inoculated with herpes virus type 1.

The variation of lactate dehydrogenase, peroxidase, acid and alkaline phosphatase isoenzymes was studied in VERO cells inoculated with infectant and UV-inactivated herpes simplex virus type 1 (HSV--1). Infectant HSV--1 induced quantitative and qualitative modifications in isoenzyme patterns within the first 4 hours post inoculation (p.i.). The modifications caused by the UV-inactivated HSV--1 were similar, but appeared 8 hours p.i. The possibility of using isoenzyme modifications as rapid, sensitive and specific biochemical tests for virus detection and differentiation between infectant and inactivated virus is discussed.

Acid Phosphatase↗
PubMed1996

Serine/threonine protein phosphatases and a protein phosphatase 1 inhibitor from Neurospora crassa.

The major spontaneously active serine/threonine (Ser/Thr) protein phosphatase activities in N. crassa wild type (FGSC 424) were type-1 (PP1), type-2A (PP2A) and type-2C (PP2C). PP1 and PP2C predominantly dephosphorylated phosphorylase a and casein, respectively. PP2A acted on both substrates, but was two-fold more active against casein. PP1 activity was inhibited by protamine, heparin, okadaic acid (IC50 50 nM) and mammalian inhibitor-1 (IC50 2 nM). On the other hand. PP2A activity was inhibited by much lower concentrations of okadaic acid (IC50 0.2 nM) and also by protamine, but not by heparin or inhibitor-1. About 80% of total PP1 activity was associated with the particulate fraction and could be partially extracted with 0.5 M NaCl. Seventy and ninety percent of PP2A and PP2C activities, respectively, were found in the soluble fraction. In addition we have partially purified an acid and thermostable PP1 inhibitor which effectively inhibits both N. crassa and mammalian PP1.

Animals↗
PubMed1995

Effects of anoxia on protein phosphatase in turtle organs: purification and properties of protein phosphatase type-1 from turtle liver.

Protein phosphatase type 1 (PP-1) was analyzed in organs of the red-eared slider turtle, Trachemys scripta elegans, a species capable of long-term anoxia survival. During anoxic submergence at 7 degrees C, PP-1 activity in liver rapidly decreased to 63% of the control value within the first hour and remained suppressed over the subsequent 20 h of anoxia. PP-1 activity was also suppressed in red skeletal muscle during anoxia and dropped transiently (after 1 h) in brain but did not change in heart or white muscle. PP-1 was purified from turtle liver using polyethylene glycol fractionation and chromatography on DEAE-cellulose, blue dextran, Sephacryl S-200, and ADP-agarose. A 3000-fold purification was achieved with a final specific activity of 3156 nmol released min-1 mg protein-1 using 32P-labeled phosphorylase a as the substrate. Turtle liver PP-1 was a monomer of molecular mass 37 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis or 38 +/- 2 kDa by Sephacryl S-200 gel filtration. The enzyme was inhibited by okadaic acid (Ki 12.6 +/- 1.4 nM) and AMP (Ki 23 +/- 2 microM) as well as by ADP, ATP, and IMP. Regulation of liver PP-1 appears to be an integral part of anoxia-induced changes in liver glycogenolysis and metabolic rate suppression.

Adenosine Monophosphate↗
PubMed1995

Paradoxical effects of phosphate to directly regulate the level of skeletal alkaline phosphatase activity in human osteosarcoma (SaOS-2) cells and inversely regulate the level of skeletal alkaline phosphatase mRNA.

Recent studies indicate that the amount of alkaline phosphatase (ALP) activity in human osteoblast-line cells is proportional to the concentration of phosphate in the culture medium. The current studies were intended to extend those observations and to determine whether the effects of phosphate (and phosphate esters and analogs) to alter the cellular level of ALP activity, in human osteosarcoma SaOS-2 cells, reflected regulation at the level of transcription. Consistent with previous findings, we found direct, time- and dose-dependent correlations between the concentration of phosphate and the amount of ALP activity/mg cell protein (P < 0.05). Surprisingly, we also found a negative correlation between the phosphate concentration in the medium and the level of skeletal ALP mRNA (e.g., r = -0.98, P < 0.01 at 24 hours). As the highest cellular levels of skeletal ALP activity were associated with the lowest levels of ALP mRNA, these data indicated that the phosphate-dependent increase in ALP activity was not mediated by an increase in transcription and, conversely, that the effect of phosphate withdrawal to decrease ALP activity was not mediated by a decrease in transcription.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1995

Phosphate regulates the stability of skeletal alkaline phosphatase activity in human osteosarcoma (SaOS-2) cells without equivalent effects on the level of skeletal alkaline phosphatase immunoreactive protein.

Inorganic phosphate (P(i)) can regulate the level of skeletal alkaline phosphatase (ALP) activity in human osteoblast-like cells, but not by means of changes in transcription or release from the cell surface. The current studies were intended to determine whether (1) P(i) affected the inactivation of ALP activity in human osteosarcoma (SaOS-2) cells; and (2) P(i)-dependent changes in ALP-specific activity were associated with equal, concomitant changes in the level of ALP immunoreactive protein. The results of these studies revealed that P(i) increased the stability of skeletal ALP activity without equivalent effects on the level of ALP immunoreactive protein. An increase in P(i) (from 0 to 1.8 mmol/liter) caused a time-dependent increase in the amount of skeletal ALP activity in the SaOS-2 cells, without a parallel increase in the amount of skeletal ALP immunoreactive protein, and a decrease in P(i) (from 1.8 to 0 mmol/liter) caused a time-dependent decrease in the amount of ALP activity, without a significant decrease in the total cellular content of ALP immunoreactive protein. Together, these observations suggest that P(i) may alter the level of skeletal ALP activity in SaOS-2 cells by inhibiting a process of irreversible inactivation that does not effect equal, concomitant changes in the level of skeletal ALP immunoreactive protein.

Alkaline Phosphatase↗
PubMed1997

Stable transfection of nonosteogenic cell lines with tissue nonspecific alkaline phosphatase enhances mineral deposition both in the presence and absence of beta-glycerophosphate: possible role for alkaline phosphatase in pathological mineralization.

It is documented that alkaline phosphatase (AP) plays an important role in bone mineralization. Considering that TN-AP is expressed in periodontal ligament fibroblasts, renal epithelial cells, and vascular endothelial cells, and that TN-AP is both a calcium-/phosphate-binding protein and a phosphohydrolytic enzyme, we hypothesize that membrane-bound AP also plays an important role in the initiation of physiological and pathological mineralizations in tissues other than bone and cartilage. To test this hypothesis, nonosteoblast cell lines, including a fibroblast line, a renal epithelial line, and a capillary endothelial line, were stably transfected to express high levels of rat bone AP on their cell surfaces. These rat bone AP-expressing cells were then cultured on filter membranes in the presence or absence of beta-glycerol phosphate. von Kossa staining for calcium phosphate and transmission electron microscopy with electron diffraction analysis for minerals were employed to investigate the effect of membrane AP on extracellular calcium phosphate mineralization. Our results indicated that AP expression on these nonosteoblast-like cell surfaces have induced extracellular hydroxyapatite (HAP) mineralization. Our findings support the concept that membrane-bound AP contributes to extracellular apatitic mineralization by mechanisms that do not necessarily involve its hydrolase activity. They also suggest that AP might be important for the initiation of pathological mineralization in nonosteogenic tissues.

Alkaline Phosphatase↗
PubMed2006

Positive placental staining for alkaline phosphatase corresponding with extreme elevation of serum alkaline phosphatase during pregnancy.

Placental ALP (ALP(h)) is a membrane-anchored, heat-stable enzyme produced by the syncytiotrophoblast. We report a case of a patient presenting in the third trimester with extreme increased levels of ALP(h). A 40-year-old woman, gravida 2, para 1, was admitted to the high risk pregnancy unit at 30 weeks of gestation for evaluation of an incidental finding of marked isolated elevation in serum ALP(h). Blood tests obtained at admission revealed a marked elevation of serum ALP level up to 1,194 u/l (reference 35-104 u/l). At 36 weeks of gestation, the patient was admitted with preterm premature rupture of membranes. Due to breech presentation, a cesarean delivery was performed. An immunoperoxidase stain was done for placental alkaline phosphatase, which was positive in the majority of chorionic trophoblastic cells. No evidence of inflammation was detected in the placental chorionic plate. Thus, isolated elevation in placental ALP may be linked to a subsequent preterm delivery.

Adult↗