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Cloning and expression of cDNA encoding the human 150 kDa oxygen-regulated protein, ORP150
J Ikeda1, S Kaneda, K Kuwabara
1HSP Research Institute, Kyoto Research Park, Shimogyo-ku, Japan.
Abstract:
We have cloned a cDNA encoding the human 150 kDa oxygen-regulated protein (ORP150) from hypoxia-treated astrocytoma U373 cDNA library. The deduced amino acid sequence of 999 residues contains a signal peptide and an ER retention-like signal at the N- and C-termini, respectively. It has a striking sequence similarity (91% identity) with Chinese hamster 170 kDa glucose-regulated protein (GRP170). The N-terminal half of ORP150 exhibits significant similarity to the ATPase domain of HSP70 family proteins with well-conserved ATP binding motifs. Northern blot analysis revealed that induction of ORP150 in U373 cells was not limited to hypoxia but also observed by 2-deoxyglucose or tunicamycin treatment. Furthermore, tissue specificity of expression of ORP150 was quite similar to that of GRP78. These findings suggest that ORP150 participates in quality control of proteins in the ER in response to diverse environmental stresses.
Insights
We identified the human oxygen-regulated protein 150 kDa (ORP150) involved in cellular stress responses. ORP150 is expressed in the endoplasmic reticulum and aids in protein quality control under various stress conditions.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- The endoplasmic reticulum (ER) is crucial for protein folding and quality control.
- Cellular stress, such as hypoxia, can disrupt ER homeostasis.
- Understanding stress-response proteins is vital for cellular health research.
Purpose of the Study:
- To clone and characterize the human oxygen-regulated protein 150 kDa (ORP150).
- To investigate the role of ORP150 in cellular responses to environmental stress.
Main Methods:
- Cloning of ORP150 cDNA from a hypoxia-treated astrocytoma cell line.
- Sequence analysis to identify functional domains.
- Northern blot analysis to determine gene expression patterns.
Main Results:
- ORP150 shares high sequence similarity with hamster GRP170 and contains an ATPase domain similar to HSP70.
- ORP150 expression is induced by hypoxia, 2-deoxyglucose, and tunicamycin.
- Tissue expression patterns of ORP150 resemble those of GRP78.
Conclusions:
- ORP150 is a stress-inducible protein with a role in the endoplasmic reticulum.
- ORP150 likely functions in protein quality control during diverse cellular stresses.
- ORP150 represents a novel component of the cellular stress response machinery.