Biochemical characteristics of the Ca2+ pumping ATPase in the peribacteroid membrane from broad bean root nodules
Valeriya Krylova1, Igor M Andreev, Rozaliya Zartdinova
1Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, 127276, Botanicheskaya st. 35, Russia. KrylovaVV@list.ru
Abstract:
Ca(2+)-ATPase in the peribacteroid membrane (PBM) of symbiosomes isolated from Vicia faba root nodules was characterized in terms of its hydrolytic and transport activities. Both activities were found to be pH-dependent and exhibit pH optimum at pH 7.0. Translocation of Ca(2+) through the PBM by the Ca(2+)-ATPase was shown to be fueled by ATP and other nucleotide triphosphates in the following order: ATP > ITP ≅ GTP ≅ UTP ≅ CTP, the K m of the enzyme for MgATP being about 100 μM. Ca-dependent ITP-hydrolytic activity of symbiosomes was investigated in the presence of the Ca-EGTA buffer system and showed the affinity of PBM Ca(2+)-ATPase for Ca(2+) of about 0.1 μM. The transport activity of Ca(2+)-ATPase was inhibited by erythrosin B as well as orthovanadate, but markedly stimulated by calmodulin from bovine brain. These results allowed us to conclude that this enzyme belongs to IIB-type Ca(2+)-ATPases which are present in other plant membranes.
Related Concept Videos
ATP Driven Pumps II: P-type Pumps
A typical P-type pump has three cytosolic domains: nucleotide-binding (N), phosphorylation (P), and activator (A) domains. These domains are connected to the membrane-spanning helices by short amino acid segments. ATP hydrolysis and covalent phosphoenzyme intermediate formation are crucial parts of the catalytic cycle. At the highly...
ATP Driven Pumps I: An Overview
There are four main types of ATP-driven pumps - P-type, V-type, F-type, and ABC transporter. All these pumps are of varying complexities and are...
ATP Driven Pumps III: V-type Pumps
The peripheral or cytosolic V1 domain with eight subunits is involved in ATP hydrolysis. The integral or transmembrane V0 domain containing at least five subunits...
ATP Synthase: Structure
Primary Active Transport
Primary Active Transport


