The human gene ATP 13A2 has been proposed to code for an ATP powered ion transporter of the PsB subfamily. Mutations of the human gene ATP1 3A2 were found to underlie an autosomal recessive form of early-onset parkins...The human gene ATP 13A2 has been proposed to code for an ATP powered ion transporter of the PsB subfamily. Mutations of the human gene ATP1 3A2 were found to underlie an autosomal recessive form of early-onset parkinsonism （PD） with pyramidal degeneration and dementia. The ion transported by the ATP13A2 pump is not known, but several studies have shown that the Ps-ATPases influence the homeostasis of intracellular Ca2＋, and thus it has been suggested that they transport Ca2＋. In order to evaluate this possibility Chinese hamster ovary （CHO） cells stably expressing the human ATP13A2 protein have been obtained and the Ca2＋ transport activity of ATP 13A2 was assessed by measuring the ATP-dependent uptake of Ca2＋ into microsomal vesicles. As a positive control vesicles containing the human plasma membrane Ca2＋ pump （PMCA） were used. No significant differences were found between vesicles containing the ATP 13A2 protein and the control. Moreover, Ca2＋ was unable to induce the formation of the P-ATPase acylphosphate intermediate in vesicles containing the expressed ATPl3A2. These results favor the idea that the ATPI3A2 does not transport Ca2＋.展开更多
文摘The human gene ATP 13A2 has been proposed to code for an ATP powered ion transporter of the PsB subfamily. Mutations of the human gene ATP1 3A2 were found to underlie an autosomal recessive form of early-onset parkinsonism （PD） with pyramidal degeneration and dementia. The ion transported by the ATP13A2 pump is not known, but several studies have shown that the Ps-ATPases influence the homeostasis of intracellular Ca2＋, and thus it has been suggested that they transport Ca2＋. In order to evaluate this possibility Chinese hamster ovary （CHO） cells stably expressing the human ATP13A2 protein have been obtained and the Ca2＋ transport activity of ATP 13A2 was assessed by measuring the ATP-dependent uptake of Ca2＋ into microsomal vesicles. As a positive control vesicles containing the human plasma membrane Ca2＋ pump （PMCA） were used. No significant differences were found between vesicles containing the ATP 13A2 protein and the control. Moreover, Ca2＋ was unable to induce the formation of the P-ATPase acylphosphate intermediate in vesicles containing the expressed ATPl3A2. These results favor the idea that the ATPI3A2 does not transport Ca2＋.
