Plant Molecular Biology

, Volume 75, Issue 4–5, pp 413–430 | Cite as

Plant aquaporins with non-aqua functions: deciphering the signature sequences



Research in recent years on plant Major Intrinsic Proteins (MIPs), commonly referred to as ‘aquaporins’, has seen a vast expansion in the substrates found to be transported via these membrane channels. The diversity in sizes, chemical nature and physiological significance of these substrates has meant a need to critically analyse the possible structural and biochemical properties of MIPs that transport these, in order to understand their roles. In this work we have undertaken a comprehensive analysis of all plant MIPs, coming from different families, that have been proven to transport ammonia, boron, carbon dioxide, hydrogen peroxide, silicon and urea. The sequences were analysed for all primary selectivity-related motifs (NPA motifs, ar/R filter, P1–P5 residues). In addition, the putative regulatory phosphorylation and glycosylation sites and mechanistic regulators such as loop lengths have been analysed. Further, nine specificity-determining positions (SDPs) were predicted for each group. The results show the ar/R filter residues, P2–P4 positions and some of the SDPs are characteristic for certain groups, and O-glycosylation sites are unique to a subgroup while N-glycosylation was characteristic of the other MIPs. Certain residues, especially in loop C, and structural parameters such as loop lengths also contribute to the uniqueness of groups. The comprehensive analysis makes significant inroads into appraising the intriguing diversity of plant MIPs and their roles in fundamental life processes, and provides tools for plant selections, protein engineering and transgenics.


Aquaporins Major intrinsic proteins Membrane channels Abiotic stress 



Alanine-glutamic acid-phenyl alanine


GlpF-like intrinsic proteins


Hybrid intrinsic proteins


Major intrinsic proteins


NOD26-like intrinsic proteins






Residues at P1 to P5 positions


Plasma membrane intrinsic proteins


Tonoplast intrinsic proteins


Transmembrane helix


Small, basic intrinsic proteins


Uncategorized X intrinsic proteins

Supplementary material

11103_2011_9737_MOESM1_ESM.doc (309 kb)
Supplementary material 1 (DOC 309 kb)
11103_2011_9737_MOESM2_ESM.doc (276 kb)
Supplementary material 2 (DOC 276 kb)


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Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  1. 1.Environment and Biotechnology Centre, Faculty of Life and Social SciencesSwinburne University of TechnologyHawthornAustralia

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