title: Novel type aquaporin SIPs are mainly localized to the ER membrane and show cell-specific expression in Arabidopsis thaliana.
abstract: We investigated the fourth subgroup of Arabidopsis aquaporin, small and basic intrinsic proteins (SIPs). When they were expressed in yeast, SIP1;1 and SIP1;2, but not SIP2;1, gave water-channel activity. The transient expression of SIPs linked with green fluorescent protein in Arabidopsis cells and the subcellular fractionation of the tissue homogenate showed their ER localization. The SIP proteins were detected in all of the tissues, except for dry seeds. Histochemical analysis of promoter-beta-glucuronidase fusions revealed the cell-specific expression of SIPs. SIP1;1 and SIP1;2 may function as water channels in the ER, while SIP2;1 might act as an ER channel for other small molecules or ions.
authors.affiliation: Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Japan.
authors.forename: Fumiyoshi
authors.initials: F
authors.lastname: Ishikawa
authors.forename: Shinobu
authors.initials: S
authors.lastname: Suga
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Uemura
authors.forename: Masa H
authors.initials: MH
authors.lastname: Sato
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Maeshima
mesh_terms: D020346:Aquaporins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000737:chemistry / Q000378:metabolism*; D015870:Gene Expression; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics; D007425:Intracellular Membranes / Q000737:chemistry / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics; D014018:Tissue Distribution
chemical_list: D020346:Aquaporins; D029681:Arabidopsis Proteins; D049452:Green Fluorescent Proteins; C506075:SIP1A protein, Arabidopsis; C506076:SIP1;2 protein, Arabidopsis; C506077:SIP2;1 protein, Arabidopsis