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lonomycin-regulated phosphorylation of the myeloid calcium-binding protein p14

lonomycin-regulated phosphorylation of the myeloid calcium-binding protein p14 Two associated calcium-binding proteins (CaBPs) have recently been identified specifically in cells of myeloid origin. These proteins have relative molecular masses (Mr) of 8,000 and 14,000 and are variously referred to as the cystic fibrosis antigen1, the LI light chain2, MRP-8 (ref. 3) or p8, and the LI heavy chain2, MRP14 (ref. 3) or pi4, respectively. The expression of p8 and p14 seems to be confined to a specific stage of myeloid cell differentiation, because both proteins are expressed in circulating neutrophils and monocytes but not in normal tissue macrophages4,5. In chronic inflammatory conditions, however, such as rheumatoid arthritis, macrophages in affected tissues express both p8 and p14 (refs 4, 6, 7). These proteins are members of a family of CaBPs of low Mr (ref. 8), which include S-100 α and β proteins9,10, calcyclin (2A9)11, intestinal CaBP12 and p11 (ref. 13). All the proteins have an Mr of ∼10,000 with the exception of p14 which has a longer C-terminal sequence after the second calcium-binding domain. Little is known about their function, although by analogy with calmodulin they could be molecules involved in intracellular signalling that are activated by an increase in the intracellular Ca2+ concentration ([Ca2+]i) (ref. 14). Here we report that p14 is phos-phorylated in both monocytes and neutrophils. The level of p14 phosphorylation can be increased by elevating the [Ca2+]1 using the ionophore ionomycin, but is not affected by activation of protein kinase C using phorbol 12,13-dibutyrate. The phosphorylated residue is threonine at position 113, which is the penultimate amino acid in p14 and contained in the longer 'tail' sequence. Part of this sequence is identical15 to the neutrophil immobilizing factors NIF-1 and NIF-2 (ref. 16), indicating that the phosphorylation event could have a role in the generation of NIF activity in the p14 protein. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Nature Springer Journals

lonomycin-regulated phosphorylation of the myeloid calcium-binding protein p14

Edgeworth, Jonathan; Freemont, Paul; Hogg, Nancy
Nature , Volume 342 (6246) – Nov 9, 1989
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References (26)

Publisher
Springer Journals
Copyright
Copyright © 1989 by Nature Publishing Group
Subject
Science, Humanities and Social Sciences, multidisciplinary; Science, Humanities and Social Sciences, multidisciplinary; Science, multidisciplinary
ISSN
0028-0836
eISSN
1476-4687
DOI
10.1038/342189a0
Publisher site
See Article on Publisher Site

Abstract

Two associated calcium-binding proteins (CaBPs) have recently been identified specifically in cells of myeloid origin. These proteins have relative molecular masses (Mr) of 8,000 and 14,000 and are variously referred to as the cystic fibrosis antigen1, the LI light chain2, MRP-8 (ref. 3) or p8, and the LI heavy chain2, MRP14 (ref. 3) or pi4, respectively. The expression of p8 and p14 seems to be confined to a specific stage of myeloid cell differentiation, because both proteins are expressed in circulating neutrophils and monocytes but not in normal tissue macrophages4,5. In chronic inflammatory conditions, however, such as rheumatoid arthritis, macrophages in affected tissues express both p8 and p14 (refs 4, 6, 7). These proteins are members of a family of CaBPs of low Mr (ref. 8), which include S-100 α and β proteins9,10, calcyclin (2A9)11, intestinal CaBP12 and p11 (ref. 13). All the proteins have an Mr of ∼10,000 with the exception of p14 which has a longer C-terminal sequence after the second calcium-binding domain. Little is known about their function, although by analogy with calmodulin they could be molecules involved in intracellular signalling that are activated by an increase in the intracellular Ca2+ concentration ([Ca2+]i) (ref. 14). Here we report that p14 is phos-phorylated in both monocytes and neutrophils. The level of p14 phosphorylation can be increased by elevating the [Ca2+]1 using the ionophore ionomycin, but is not affected by activation of protein kinase C using phorbol 12,13-dibutyrate. The phosphorylated residue is threonine at position 113, which is the penultimate amino acid in p14 and contained in the longer 'tail' sequence. Part of this sequence is identical15 to the neutrophil immobilizing factors NIF-1 and NIF-2 (ref. 16), indicating that the phosphorylation event could have a role in the generation of NIF activity in the p14 protein.

Journal

Nature – Springer Journals

Published: Nov 9, 1989

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