In a previous paper, we showed that @entity1507 reductase (NR; EC 1.6.6.1) from leaves of @entity9377 . differed from most other higher-plant NRs by an unusually strong @entity1025 -sensitivity, a different pH-activity profile and only little @entity855 -dependent inactivation [A. Kandlbinder et al. (2000) J Exp Bot 51:1099-1105]. In order to elucidate these deviating properties in more detail, the NR gene from @entity9377 was cloned, expressed heterologously and characterized. The deduced protein sequence showed that Ricinus NR has a @entity563 phosphorylation site and a 14-3-3 binding motif, a common characteristic of NRs. Functional Ricinus NR protein was expressed in the @entity375 @entity10056 and compared with the features of @entity958 @entity31389 synthesized by the same expression system ( @entity31389 ). The recombinant Ricinus NR (RcNR) itself was not inactivated by incubation with Mg @entity855 . As @entity375 extracts might lack factors required for NR regulation, desalted leaf extracts containing NR kinases and 14-3-3 proteins were prepared from 4-day-darkened (and therefore NR-free) leaves of Ricinus, and added to the assay of RcNR to check for @entity855 -dependent inactivation and @entity1025 -sensitivity. When RcNR was combined with the NR-free extracts described above, its unusually high @entity1025 -sensitivity was restored, but it remained unresponsive to @entity855 . In contrast, @entity31389 became inactive when incubated with the protein mixture and @entity855 . Thus, insensitivity to @entity855 appears to be an inherent property of Ricinus NR, whereas the high @entity1025 -sensitivity depends on one or several factors in Ricinus leaves. This as yet unknown factor(s) was boiling-sensitive and appeared to interact specifically with recombinant Ricinus NR to provide the @entity1025 -sensitivity of the authentic leaf enzyme.

Molecular cloning and characterization of @entity1507 reductase from @entity9377 . heterologously expressed in XXXX .

@entity1025 :: ('CHEBI:18420', 'Chemical') :: ['Mg2+'] @entity9377 :: ('3988', 'Species') :: ['R. communis', 'Ricinus communis L'] @entity10056 :: ('4922', 'Species') :: ['Pichia pastoris'] @entity958 :: ('3702', 'Species') :: ['Arabidopsis thaliana'] @entity1507 :: ('CHEBI:48107', 'Chemical') :: ['nitrate'] @entity31389 :: ('840630(Tax:3702)', 'Gene') :: ['AtNR2', 'NR2'] @entity563 :: ('CHEBI:17822', 'Chemical') :: ['serine'] @entity375 :: ('4932', 'Species') :: ['yeast'] @entity855 :: ('MESH:D000255', 'Chemical') :: ['ATP']
@entity10056 :: (4922,Species) :: ['Pichia pastoris']
