Membrane-anchored prolyl hydroxylase with an export signal from the endoplasmic reticulum
Article first published online: 12 NOV 2004
The Plant Journal
Volume 41, Issue 1, pages 81–94, January 2005
How to Cite
Yuasa, K., Toyooka, K., Fukuda, H. and Matsuoka, K. (2005), Membrane-anchored prolyl hydroxylase with an export signal from the endoplasmic reticulum. The Plant Journal, 41: 81–94. doi: 10.1111/j.1365-313X.2004.02279.x
- Issue published online: 12 NOV 2004
- Article first published online: 12 NOV 2004
- Received 1 July 2004; revised 22 September 2004; accepted 27 September 2004.
- prolyl hydroxylase;
- membrane protein;
- tobacco BY-2 cells;
- secretory pathway;
- export signal
We cloned a novel prolyl 4-hydroxylase (PH; EC 22.214.171.124) homolog cDNA from tobacco (Nicotiana tabacum) BY-2 cells based on expression sequence tag information. Like other PHs, this tobacco PH polypeptide has two conserved histidine residues, and it comprises 286 amino acids with a calculated molecular mass of 32 kDa. Interestingly, this protein and homologs in Arabidopsis and rice have predicted transmembrane sequences in their N-terminal regions. This PH homolog was expressed in BY-2 cells as a His-tagged protein, and the expressed protein showed PH activity. Incubation of membranes with high salt, urea, and protease with or without detergents indicated that this protein is an integral membrane protein with a type II configuration. Its membrane-anchored nature is specific for plants because no integral membrane PH has been found in animals. A membrane fractionation study and immunocytochemical studies indicate that this protein localizes in both the endoplasmic reticulum (ER) and Golgi apparatus. Analysis of this protein fused to green fluorescent protein indicated that basic amino acids in the cytoplasmic, N-terminal region of the PH play a role in its export from the ER.