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Phosphorylase a activity as an indicator of neutrophil activation by chemotactic peptide
The activity of glycogen phosphorylase, an enzyme that is activated by both cAMP and calcium, was used as an indicator of the state of the cytoplasm after chemotactic stimulation of polymorphonuclear leukocytes (neutrophils). The activity of the enzyme showed a clear dependence on cytoplasmic calciu...
Formato: | Texto |
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Lenguaje: | English |
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The Rockefeller University Press
1985
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2113936/ https://www.ncbi.nlm.nih.gov/pubmed/2995402 |
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collection | PubMed |
description | The activity of glycogen phosphorylase, an enzyme that is activated by both cAMP and calcium, was used as an indicator of the state of the cytoplasm after chemotactic stimulation of polymorphonuclear leukocytes (neutrophils). The activity of the enzyme showed a clear dependence on cytoplasmic calcium. Addition of the calcium ionophore A23187 caused a 4-5-fold increase in activity of phosphorylase a. In the absence of external Ca2+, A23187 caused only brief transient activation of phosphorylase; probably reflecting release of sequestered intracellular Ca2+. Addition of the chemotactic peptide N- formylnorleucylleucylphenylalanine (FNLLP) caused a transient 2-3-fold activation of the enzyme. The dose-dependence of activation by FNLLP showed a peak at 10(-8) M, near the Kd of the receptor for FNLLP. The phosphorylase activity peaks by 90 s and then declines, returning to basal levels by 20 min after stimulation with 10(-8) M peptide and by 60 min with 10(-7) M peptide. This finding suggests that the cells do not need to maintain elevated cytoplasmic calcium levels to exhibit stimulated locomotion. Thus, if calcium continues to modulate the motility, there either must be highly localized changes that are not detected in measures of the total cytoplasm, or the sensitivity to calcium must be variable such that basal levels are sufficient to maintain locomotion. Cells loaded with the fluorescence calcium probe quin2 (0.6 mM) in the presence or absence of external Ca2+ had elevated phosphorylase levels before addition of FNLLP. Thus, the presence of quin2 may alter the cytoplasmic Ca2+ level, and it clearly alters some aspects of the neutrophil physiology. Phosphorylase a appears to be a sensitive, nonperturbing indicator of the cytoplasmic calcium levels. |
format | Text |
id | pubmed-2113936 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 1985 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-21139362008-05-01 Phosphorylase a activity as an indicator of neutrophil activation by chemotactic peptide J Cell Biol Articles The activity of glycogen phosphorylase, an enzyme that is activated by both cAMP and calcium, was used as an indicator of the state of the cytoplasm after chemotactic stimulation of polymorphonuclear leukocytes (neutrophils). The activity of the enzyme showed a clear dependence on cytoplasmic calcium. Addition of the calcium ionophore A23187 caused a 4-5-fold increase in activity of phosphorylase a. In the absence of external Ca2+, A23187 caused only brief transient activation of phosphorylase; probably reflecting release of sequestered intracellular Ca2+. Addition of the chemotactic peptide N- formylnorleucylleucylphenylalanine (FNLLP) caused a transient 2-3-fold activation of the enzyme. The dose-dependence of activation by FNLLP showed a peak at 10(-8) M, near the Kd of the receptor for FNLLP. The phosphorylase activity peaks by 90 s and then declines, returning to basal levels by 20 min after stimulation with 10(-8) M peptide and by 60 min with 10(-7) M peptide. This finding suggests that the cells do not need to maintain elevated cytoplasmic calcium levels to exhibit stimulated locomotion. Thus, if calcium continues to modulate the motility, there either must be highly localized changes that are not detected in measures of the total cytoplasm, or the sensitivity to calcium must be variable such that basal levels are sufficient to maintain locomotion. Cells loaded with the fluorescence calcium probe quin2 (0.6 mM) in the presence or absence of external Ca2+ had elevated phosphorylase levels before addition of FNLLP. Thus, the presence of quin2 may alter the cytoplasmic Ca2+ level, and it clearly alters some aspects of the neutrophil physiology. Phosphorylase a appears to be a sensitive, nonperturbing indicator of the cytoplasmic calcium levels. The Rockefeller University Press 1985-10-01 /pmc/articles/PMC2113936/ /pubmed/2995402 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/). |
spellingShingle | Articles Phosphorylase a activity as an indicator of neutrophil activation by chemotactic peptide |
title | Phosphorylase a activity as an indicator of neutrophil activation by chemotactic peptide |
title_full | Phosphorylase a activity as an indicator of neutrophil activation by chemotactic peptide |
title_fullStr | Phosphorylase a activity as an indicator of neutrophil activation by chemotactic peptide |
title_full_unstemmed | Phosphorylase a activity as an indicator of neutrophil activation by chemotactic peptide |
title_short | Phosphorylase a activity as an indicator of neutrophil activation by chemotactic peptide |
title_sort | phosphorylase a activity as an indicator of neutrophil activation by chemotactic peptide |
topic | Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2113936/ https://www.ncbi.nlm.nih.gov/pubmed/2995402 |