TY - JOUR
T1 - In vivo treatments that modulate PPi-dependent H+ transport activity of tonoplast-enriched membrane vesicles from barley roots
AU - Kasai, Minobu
AU - Sasaki, Masao
AU - Yamamoto, Yoko
AU - Matsumoto, Hideaki
N1 - Funding Information:
Barley seeds were kindly supplied by the Barley Germplasm Center of our Institute. This research was supported by a Grant-in-Aid for General Scientific Research (no. 03660069) from the Ministry of Education, Science and Culture, Japan.
PY - 1993/6
Y1 - 1993/6
N2 - The PPi-dependent H+ transport activity of tonoplast-enriched membrane vesicles prepared from barley roots was greatly reduced when the plants were grown for 4 or 5 days with an additional 3 raM KC1 in growth medium that contained only 0.1 mM CaCl2 in water. To characterize the mechanism of this reduction in activity, we attempted to treat barley roots with K+ ions, Cl-ions (or acetate), and A23187 (with or without Ca2+ ions), which might be expected to cause alkalization, acidification and mobilization of Ca2+ ions in the cytoplasm, respectively. One-day treatment of barley roots with K+ ions significantly decreased PPi--dependent H+ transport activity of prepared tonoplast-enriched membrane vesicles, while treatment with Cl- ions or acetate significantly increased the activity. A similar increase in the activity also occurred by treatment with Ca2+ ions alone or in combination with A23187. Determination of the PPi-hydrolyzing activity of membrane vesicles showed that changes in this activity by the various treatments were similar to those in the PPi-dependent H+ transport activity. The changes in ATP-dependent H+ transport activity of membrane vesicles caused by these treatments were small. These results indicate that the in vivo treatments had significant effects on the H+ transport activity of H+-PPi-ase, one of the two active vacuolar H+-pumps (H+-PPiase and H+-ATPase). In addition, these results suggest the possibility that changes in levels of cytoplasmic H+ or Ca2+ ions may be involved in modulation of the H+ transport activity of the vacuolar H+-PPiase during plant growth.
AB - The PPi-dependent H+ transport activity of tonoplast-enriched membrane vesicles prepared from barley roots was greatly reduced when the plants were grown for 4 or 5 days with an additional 3 raM KC1 in growth medium that contained only 0.1 mM CaCl2 in water. To characterize the mechanism of this reduction in activity, we attempted to treat barley roots with K+ ions, Cl-ions (or acetate), and A23187 (with or without Ca2+ ions), which might be expected to cause alkalization, acidification and mobilization of Ca2+ ions in the cytoplasm, respectively. One-day treatment of barley roots with K+ ions significantly decreased PPi--dependent H+ transport activity of prepared tonoplast-enriched membrane vesicles, while treatment with Cl- ions or acetate significantly increased the activity. A similar increase in the activity also occurred by treatment with Ca2+ ions alone or in combination with A23187. Determination of the PPi-hydrolyzing activity of membrane vesicles showed that changes in this activity by the various treatments were similar to those in the PPi-dependent H+ transport activity. The changes in ATP-dependent H+ transport activity of membrane vesicles caused by these treatments were small. These results indicate that the in vivo treatments had significant effects on the H+ transport activity of H+-PPi-ase, one of the two active vacuolar H+-pumps (H+-PPiase and H+-ATPase). In addition, these results suggest the possibility that changes in levels of cytoplasmic H+ or Ca2+ ions may be involved in modulation of the H+ transport activity of the vacuolar H+-PPiase during plant growth.
KW - In vivo treatment
KW - PPi-dependent H+ transport
KW - Tonoplast
UR - http://www.scopus.com/inward/record.url?scp=0009863896&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0009863896&partnerID=8YFLogxK
M3 - Article
AN - SCOPUS:0009863896
VL - 34
SP - 549
EP - 555
JO - Plant and Cell Physiology
JF - Plant and Cell Physiology
SN - 0032-0781
IS - 4
ER -