Review Article
Alkaline Phosphatase in Stem Cells
Table 1
Alkaline phosphatases expressed in humans and mice with their basic attributes.
| Isoenzyme AP | Gene | Molecular weight | Tissue localization | Temperature of inactivation | Specific inhibitors |
| PLAP | ALPP | 90–120 kDa | Syncytiotrophoblast | Stable at 70°C | neuraminidase [5], L-phenylalanine [58], L-leucine [60], L-leucyl-glycyl-glycine [56], L-phenylalanyl-glycyl-glycine [56] | GCAP | ALPPL2 | PGC, testes, cervix, thymus | EAP (mouse) | Akp5 (Alppl2) | Preimplantation stage of embryo |
| IAP IAP-like (mouse) | ALPI (human) Akp3 (mouse) Akp6 (Alpi) | 70–90 kDa | Small intestine (duodenum) | Stable at 56°C | L-Phenylalanine [58], L-tryptophan [59] |
| Bone isoform TNAP | ALPL (human) Alpl (mouse) | 120–150 kDa | Bone (preosteoblastic cells, basolateral site of osteoblasts), chondrocytes, odontoblasts | PGC (mouse), brain (subependymal layer), embryo, testes (mouse) | Nonstable at 55°C |
L-Homoarginine [61], neuraminidase [5], L-levamisole [57], imidazole [62] | Liver isoform TNAP | Liver (bille epithelium) | At 55°C more stable than bone isoform | Kidney isoform TNAP | Kidney (epithelial cells of proximal tubules) | Nonstable at 45°C |
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PLAP: placental AP; GCAP: germ cell AP; EAP: embryonic AP; IAP: intestinal AP; TNAP: tissue nonspecific AP.
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