Placental alkaline phosphatase integrates via its carboxy-terminus into the microvillous membrane: Its allotypes differ in conformation
| Autor: | R.G. Sutcliffe, N. Abu-Hasan |
|---|---|
| Rok vydání: | 1985 |
| Předmět: |
Protein Conformation
Placenta Proteolysis Protein structure Pregnancy medicine Humans Cyanogen Bromide Subtilisins chemistry.chemical_classification Microvilli medicine.diagnostic_test Cell Membrane Subtilisin Obstetrics and Gynecology Alkaline Phosphatase Trypsin Peptide Fragments Amino acid Isoenzymes Phenotype Placental alkaline phosphatase Membrane Reproductive Medicine Biochemistry chemistry embryonic structures Alkaline phosphatase Female Developmental Biology medicine.drug |
| Zdroj: | Placenta. 6:391-404 |
| ISSN: | 0143-4004 |
| Popis: | Human placental microvillous alkaline phosphatase (M-PLAP) was extracted from microvilli either by butanol extraction or subtilisin proteolysis. The data indicate that subtilisin cleavage of PLAP removes a membrane-binding domain of approximately 2000 molecular weight, leaving the catalytic site intact and the protein in solution. Sequencing studies on the N-terminal 13 amino acids of both the subtilisin-cleaved and uncleaved forms of M-PLAP indicate that the enzyme is anchored to the plasma membranes by its carboxy-terminus. The N-terminal 13 amino acids of A-PLAP were the same as those of M-PLAP. Trypsin solubilization failed to release M-PLAP from these membranes and it appears to cleave a portion of molecular weight of about 9K from the amino terminus, leaving an enzymatically active portion of PLAP associated with the membrane. On SDS gels, subtilisin-cleaved M-PLAP showed an apparent dimeric molecular size larger than that of the original uncleaved enzyme, presumably due to the generation of a less compact conformational state. On starch gels, cleaved M-PLAP showed a single zone of enzyme activity with a mobility sightly greater than that of A-PLAP, which did not require the presence of Triton X-100 to enter the gel. Variations in the apparent molecular sizes of the different allelic forms of PLAP were also observed. |
| Databáze: | OpenAIRE |
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