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Updated: Jul 11, 2026
14:20
Measuring the Osmotic Water Permeability Coefficient (Pf) of Spherical Cells: Isolated Plant Protoplasts as an Example
Published on: October 8, 2014
ER membrane aquaporins in plants
Masayoshi Maeshima1, Fumiyoshi Ishikawa
1Laboratory of Cell Dynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan. maeshima@agr.nagoya-u.ac.jp
Pflugers Archiv : European Journal of Physiology
|October 10, 2007
Summary
Small and basic intrinsic proteins (SIPs) are plant aquaporins with unique structural features. Some SIPs transport water and are localized to the ER membrane in Arabidopsis thaliana.
Area of Science:
- Plant molecular biology
- Membrane transport proteins
Background:
- Aquaporins facilitate water and solute transport across membranes.
- The plant aquaporin superfamily comprises over 30 members in four subfamilies: PIP, TIP, NIP, and SIP.
- SIP members exhibit distinct structural characteristics, including short N-terminal tails and variations in conserved motifs.
Purpose of the Study:
- To provide an overview of the main features of SIP members.
- To highlight structural variations, ER membrane localization, and physiological functions of SIPs.
- To discuss mammalian homologues of plant SIPs.
Main Methods:
- Comparative analysis of primary structures of SIP members.
- Review of existing literature on SIP localization and function.
- Examination of gene expression profiles and protein abundance.
Main Results:
- SIPs possess unique primary structures, with altered NPA motifs in some members (SIP1;1, SIP1;2, SIP2;1).
- SIP1;1 and SIP1;2 exhibit water transport activity, while SIP2;1 does not.
- All studied SIP members are localized to the ER membrane and show cell-specific expression in Arabidopsis thaliana.
Conclusions:
- SIP aquaporins display specialized structural and functional properties.
- ER membrane localization and cell-specific expression suggest unique roles for SIPs in plant physiology.
- Further research into SIP function and regulation is warranted.
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