A Single Gene May Encode Differentially Localized Ca2+-ATPases in Tomato.

Abstract

Previously, a partial-length cDNA and a complete genomic clone encoding a putative sarcoplasmic reticulum-type Ca2+-ATPase (LCA, Lycopersicon _CaZ+-.ATPase) were isolated from tomato. To determine the subcellular localization of this Ca2+-ATPase, specific polyclonal antibodies raised against a fusion protein encoding a portion of the LCA polypeptide were generated. Based on hybridization of the LCA cDNA and of the nucleotide sequence encoding the fusion protein to genomic DNA, it appears that LCA and the fusion protein domain are encoded by a single gene in tomato. Antibodies raised against the LCA domain fusion protein reacted specifically with two polypeptides of 116 and 120 kD that are localized in the vacuolar and plasma membranes, respectively. The distribution of vanadate-sensitive ATP-dependent Ca2+ transport activities in sucrose gradients coincided with the distribution of the immunodetected proteins. The ATPdependent Ca2+ transport activities associated with tonoplast and plasma membrane fractions shared similar properties, because both fractions were inhibited by vanadate but insensitive to carbonyl cyanide m-chlorophenylhydrazone, nitrate, and calmodulin. Moreover, antibodies raised against the LCA domain fusion protein inhibited ATP-dependent Ca2+ uptake activity associated with both the tonoplast and plasma membrane fractions. These data suggest that a single gene (LCA) may encode two P-type Ca2+-ATPase isoforms that are differentially localized in the tonoplast and plasma membrane of tomato roots.

Genome‐wide expressional and functional analysis of calcium transport elements during abiotic stress and development in rice

“…However, in yeast PMR1, a P‐type ATPase was localized to Golgi bodies and was required for normal secretory processes . Similar to localization of OsECA2 in the plasma membrane in our study, one of the Lycopersicon ECAs was detected at the plasma membrane . However, Arabidopsis ECA1 was ER localized suggesting a diverse localization pattern for the plant ECAs.…”

Calcium transport across plant membranes: mechanisms and functions

“…The P 2B ‐ATPases are known as autoinhibited Ca 2+ ‐ATPase (ACA type) and are located at both the endomembranes and the PM (Bonza & De Michelis, ; Huda et al ., ,b). It should be noted that this classification is slightly vague; there is evidence that ECAs are also localized to the tonoplast and PM (Wimmers et al ., ; Ferrol & Bennett, ). In this context, it is probably prudent to focus on the dominant location.…”

Relationship between calcium decoding elements and plant abiotic-stress resistance

“…However, the potential for other isoforms targeting to non-ER locations must be considered. In tomato, there is evidence from membrane fractionation and immunodetection, suggesting that related ER-type calcium pumps (LCA1-related) are present in the vacuolar and plasma membranes 50. In wheat root, a Ca 2+ -ATPase in plasma membranes was characterized 51, and two endomembrane Ca 2+ transporters were located in different cellular compartments: the secondary H + /Ca 2+ antiport located in the vacuolar membranes, and the primary Ca 2+ -ATPases located in the endoplasmic reticulum.…”