In examining the protein kinase components of mitogen-activated protein (MAP) kinase (MAPK) cascades that regulate the c-Jun N-terminal kinase (JNK) in Drosophila S2 cells, we previously found that distinct upstream kinases were involved in responses to sorbitol and lipopolysaccharide. Here we have extended that analysis to the possible MAPK kinase kinase kinases (MAP4Ks) in the JNK pathway. Fray, a putative Drosophila MAP4K, provided a major contribution to JNK activation by sorbitol. To explore the possible link to JNK in mammalian cells, we isolated and characterized OSR1 (oxidative stress-responsive 1), one of two human Fray homologs. OSR1 is a 58-kDa protein of 527 amino acids that is widely expressed in mammalian tissues and cell lines. Of potential regulators surveyed, endogenous OSR1 is activated only by osmotic stresses, notably sorbitol and to a lesser extent NaCl. However, OSR1 did not increase the activity of coexpressed JNK, nor did it activate three other MAPKs, p38, ERK2, and ERK5. A two-hybrid screen implicated another Ste20p family member, the p21-activated protein kinase PAK1, as an OSR1 target. OSR1 phosphorylated threonine 84 in the N-terminal regulatory domain of PAK1. Replacement of threonine 84 with glutamate reduced the activation of PAK1 by an active form of the small G protein Cdc42, suggesting that phosphorylation by OSR1 modulates the G protein sensitivity of PAK isoforms.
In examining the protein kinase components of mitogen-activated protein (MAP) kinase (MAPK) cascades that regulate the c-Jun N-terminal kinase (JNK) in Drosophila S2 cells, we previously found that distinct upstream kinases were involved in responses to sorbitol and lipopolysaccharide. Here we have extended that analysis to the possible MAPK kinase kinase kinases (MAP4Ks) in the JNK pathway. Fray, a putative Drosophila MAP4K, provided a major contribution to JNK activation by sorbitol. To explore the possible link to JNK in mammalian cells, we isolated and characterized OSR1 (oxidative stress-responsive 1), one of two human Fray homologs. OSR1 is a 58-kDa protein of 527 amino acids that is widely expressed in mammalian tissues and cell lines. Of potential regulators surveyed, endogenous OSR1 is activated only by osmotic stresses, notably sorbitol and to a lesser extent NaCl. However, OSR1 did not increase the activity of coexpressed JNK, nor did it activate three other MAPKs, p38, ERK2, and ERK5. A two-hybrid screen implicated another Ste20p family member, the p21-activated protein kinase PAK1, as an OSR1 target. OSR1 phosphorylated threonine 84 in the N-terminal regulatory domain of PAK1. Replacement of threonine 84 with glutamate reduced the activation of PAK1 by an active form of the small G protein Cdc42, suggesting that phosphorylation by OSR1 modulates the G protein sensitivity of PAK isoforms.
In examining the protein kinase components of mitogen-activated protein (MAP) kinase (MAPK) cascades that regulate the c-Jun N-terminal kinase (JNK) in Drosophila S2 cells, we previously found that distinct upstream kinases were involved in responses to sorbitol and lipopolysaccharide. Here we have extended that analysis to the possible MAPK kinase kinase kinases (MAP4Ks) in the JNK pathway. Fray, a putative Drosophila MAP4K, provided a major contribution to JNK activation by sorbitol. To explore the possible link to JNK in mammalian cells, we isolated and characterized OSR1 (oxidative stress-responsive 1), one of two human Fray homologs. OSR1 is a 58-kDa protein of 527 amino acids that is widely expressed in mammalian tissues and cell lines. Of potential regulators surveyed, endogenous OSR1 is activated only by osmotic stresses, notably sorbitol and to a lesser extent NaCl. However, OSR1 did not increase the activity of coexpressed JNK, nor did it activate three other MAPKs, p38, ERK2, and ERK5. A two-hybrid screen implicated another Ste20p family member, the p21-activated protein kinase PAK1, as an OSR1 target. OSR1 phosphorylated threonine 84 in the N-terminal regulatory domain of PAK1. Replacement of threonine 84 with glutamate reduced the activation of PAK1 by an active form of the small G protein Cdc42, suggesting that phosphorylation by OSR1 modulates the G protein sensitivity of PAK isoforms.
In examining the protein kinase components of mitogen-activated protein (MAP) kinase (MAPK) cascades that regulate the c-Jun N-terminal kinase (JNK) in Drosophila S2 cells, we previously found that distinct upstream kinases were involved in responses to sorbitol and lipopolysaccharide. Here we have extended that analysis to the possible MAPK kinase kinase kinases (MAP4Ks) in the JNK pathway. Fray, a putative Drosophila MAP4K, provided a major contribution to JNK activation by sorbitol. To explore the possible link to JNK in mammalian cells, we isolated and characterized OSR1 (oxidative stress-responsive 1), one of two human Fray homologs. OSR1 is a 58-kDa protein of 527 amino acids that is widely expressed in mammalian tissues and cell lines. Of potential regulators surveyed, endogenous OSR1 is activated only by osmotic stresses, notably sorbitol and to a lesser extent NaCl. However, OSR1 did not increase the activity of coexpressed JNK, nor did it activate three other MAPKs, p38, ERK2, and ERK5. A two-hybrid screen implicated another Ste20p family member, the p21-activated protein kinase PAK1, as an OSR1 target. OSR1 phosphorylated threonine 84 in the N-terminal regulatory domain of PAK1. Replacement of threonine 84 with glutamate reduced the activation of PAK1 by an active form of the small G protein Cdc42, suggesting that phosphorylation by OSR1 modulates the G protein sensitivity of PAK isoforms.
A series of reactions in which a signal is passed on to downstream proteins within the cell by sequential protein phosphorylation and activation of the cascade components.
In examining the protein kinase components of mitogen-activated protein (MAP) kinase (MAPK) cascades that regulate the c-Jun N-terminal kinase (JNK) in Drosophila S2 cells, we previously found that distinct upstream kinases were involved in responses to sorbitol and lipopolysaccharide. Here we have extended that analysis to the possible MAPK kinase kinase kinases (MAP4Ks) in the JNK pathway. Fray, a putative Drosophila MAP4K, provided a major contribution to JNK activation by sorbitol. To explore the possible link to JNK in mammalian cells, we isolated and characterized OSR1 (oxidative stress-responsive 1), one of two human Fray homologs. OSR1 is a 58-kDa protein of 527 amino acids that is widely expressed in mammalian tissues and cell lines. Of potential regulators surveyed, endogenous OSR1 is activated only by osmotic stresses, notably sorbitol and to a lesser extent NaCl. However, OSR1 did not increase the activity of coexpressed JNK, nor did it activate three other MAPKs, p38, ERK2, and ERK5. A two-hybrid screen implicated another Ste20p family member, the p21-activated protein kinase PAK1, as an OSR1 target. OSR1 phosphorylated threonine 84 in the N-terminal regulatory domain of PAK1. Replacement of threonine 84 with glutamate reduced the activation of PAK1 by an active form of the small G protein Cdc42, suggesting that phosphorylation by OSR1 modulates the G protein sensitivity of PAK isoforms.
In examining the protein kinase components of mitogen-activated protein (MAP) kinase (MAPK) cascades that regulate the c-Jun N-terminal kinase (JNK) in Drosophila S2 cells, we previously found that distinct upstream kinases were involved in responses to sorbitol and lipopolysaccharide. Here we have extended that analysis to the possible MAPK kinase kinase kinases (MAP4Ks) in the JNK pathway. Fray, a putative Drosophila MAP4K, provided a major contribution to JNK activation by sorbitol. To explore the possible link to JNK in mammalian cells, we isolated and characterized OSR1 (oxidative stress-responsive 1), one of two human Fray homologs. OSR1 is a 58-kDa protein of 527 amino acids that is widely expressed in mammalian tissues and cell lines. Of potential regulators surveyed, endogenous OSR1 is activated only by osmotic stresses, notably sorbitol and to a lesser extent NaCl. However, OSR1 did not increase the activity of coexpressed JNK, nor did it activate three other MAPKs, p38, ERK2, and ERK5. A two-hybrid screen implicated another Ste20p family member, the p21-activated protein kinase PAK1, as an OSR1 target. OSR1 phosphorylated threonine 84 in the N-terminal regulatory domain of PAK1. Replacement of threonine 84 with glutamate reduced the activation of PAK1 by an active form of the small G protein Cdc42, suggesting that phosphorylation by OSR1 modulates the G protein sensitivity of PAK isoforms.
Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of oxidative stress, a state often resulting from exposure to high levels of reactive oxygen species, e.g. superoxide anions, hydrogen peroxide (H2O2), and hydroxyl radicals.
IEAOrtholog Compara
Enzymatic activity
This protein acts as an enzyme. It is known to catalyze the following reaction
EC 2.7.11.1: ATP + a protein ⇄ ADP + a phosphoprotein.
In examining the protein kinase components of mitogen-activated protein (MAP) kinase (MAPK) cascades that regulate the c-Jun N-terminal kinase (JNK) in Drosophila S2 cells, we previously found that distinct upstream kinases were involved in responses to sorbitol and lipopolysaccharide. Here we have extended that analysis to the possible MAPK kinase kinase kinases (MAP4Ks) in the JNK pathway. Fray, a putative Drosophila MAP4K, provided a major contribution to JNK activation by sorbitol. To explore the possible link to JNK in mammalian cells, we isolated and characterized OSR1 (oxidative stress-responsive 1), one of two human Fray homologs. OSR1 is a 58-kDa protein of 527 amino acids that is widely expressed in mammalian tissues and cell lines. Of potential regulators surveyed, endogenous OSR1 is activated only by osmotic stresses, notably sorbitol and to a lesser extent NaCl. However, OSR1 did not increase the activity of coexpressed JNK, nor did it activate three other MAPKs, p38, ERK2, and ERK5. A two-hybrid screen implicated another Ste20p family member, the p21-activated protein kinase PAK1, as an OSR1 target. OSR1 phosphorylated threonine 84 in the N-terminal regulatory domain of PAK1. Replacement of threonine 84 with glutamate reduced the activation of PAK1 by an active form of the small G protein Cdc42, suggesting that phosphorylation by OSR1 modulates the G protein sensitivity of PAK isoforms.
In examining the protein kinase components of mitogen-activated protein (MAP) kinase (MAPK) cascades that regulate the c-Jun N-terminal kinase (JNK) in Drosophila S2 cells, we previously found that distinct upstream kinases were involved in responses to sorbitol and lipopolysaccharide. Here we have extended that analysis to the possible MAPK kinase kinase kinases (MAP4Ks) in the JNK pathway. Fray, a putative Drosophila MAP4K, provided a major contribution to JNK activation by sorbitol. To explore the possible link to JNK in mammalian cells, we isolated and characterized OSR1 (oxidative stress-responsive 1), one of two human Fray homologs. OSR1 is a 58-kDa protein of 527 amino acids that is widely expressed in mammalian tissues and cell lines. Of potential regulators surveyed, endogenous OSR1 is activated only by osmotic stresses, notably sorbitol and to a lesser extent NaCl. However, OSR1 did not increase the activity of coexpressed JNK, nor did it activate three other MAPKs, p38, ERK2, and ERK5. A two-hybrid screen implicated another Ste20p family member, the p21-activated protein kinase PAK1, as an OSR1 target. OSR1 phosphorylated threonine 84 in the N-terminal regulatory domain of PAK1. Replacement of threonine 84 with glutamate reduced the activation of PAK1 by an active form of the small G protein Cdc42, suggesting that phosphorylation by OSR1 modulates the G protein sensitivity of PAK isoforms.
In examining the protein kinase components of mitogen-activated protein (MAP) kinase (MAPK) cascades that regulate the c-Jun N-terminal kinase (JNK) in Drosophila S2 cells, we previously found that distinct upstream kinases were involved in responses to sorbitol and lipopolysaccharide. Here we have extended that analysis to the possible MAPK kinase kinase kinases (MAP4Ks) in the JNK pathway. Fray, a putative Drosophila MAP4K, provided a major contribution to JNK activation by sorbitol. To explore the possible link to JNK in mammalian cells, we isolated and characterized OSR1 (oxidative stress-responsive 1), one of two human Fray homologs. OSR1 is a 58-kDa protein of 527 amino acids that is widely expressed in mammalian tissues and cell lines. Of potential regulators surveyed, endogenous OSR1 is activated only by osmotic stresses, notably sorbitol and to a lesser extent NaCl. However, OSR1 did not increase the activity of coexpressed JNK, nor did it activate three other MAPKs, p38, ERK2, and ERK5. A two-hybrid screen implicated another Ste20p family member, the p21-activated protein kinase PAK1, as an OSR1 target. OSR1 phosphorylated threonine 84 in the N-terminal regulatory domain of PAK1. Replacement of threonine 84 with glutamate reduced the activation of PAK1 by an active form of the small G protein Cdc42, suggesting that phosphorylation by OSR1 modulates the G protein sensitivity of PAK isoforms.
Protein which catalyzes the phosphorylation of serine or threonine residues on target proteins by using ATP as phosphate donor. Such phosphorylation may cause changes in the function of the target protein. Protein kinases share a conserved catalytic core common to both serine/ threonine and tyrosine protein kinases.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.
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