title: Unraveling aquaporin interaction partners.
abstract: BACKGROUND
  Insight into protein-protein interactions (PPIs) is highly desirable in order to understand the physiology of cellular events. This understanding is one of the challenges in biochemistry and molecular biology today, especially for eukaryotic membrane proteins where hurdles of production, purification and structural determination must be passed.
  
  
  METHODS
  We have explored the common strategies used to find medically relevant interaction partners of aquaporins (AQPs). The most frequently used methods to detect direct contact, yeast two-hybrid interaction assay and co-precipitation, are described together with interactions specifically found for the selected targets AQP0, AQP2, AQP4 and AQP5.
  
  
  CONCLUSIONS
  The vast majority of interactions involve the aquaporin C-terminus and the characteristics of the interaction partners are strikingly diverse. While the well-established methods for PPIs are robust, a novel approach like bimolecular fluorescence complementation (BiFC) is attractive for screening many conditions as well as transient interactions. The ultimate goal is structural evaluation of protein complexes in order to get mechanistic insight into how proteins communicate at a molecular level.
  
  
  CONCLUSIONS
  What we learn from the human aquaporin field in terms of method development and communication between proteins can be of major use for any integral membrane protein of eukaryotic origin. This article is part of a Special Issue entitled Aquaporins.
authors.affiliation: Department of Chemistry and Molecular Biology, University of Gothenburg, P.O. Box 462, SE-405 30 Göteborg, Sweden.
authors.forename: Jennie
authors.initials: J
authors.lastname: Sjöhamn
authors.affiliation: Department of Chemistry and Molecular Biology, University of Gothenburg, P.O. Box 462, SE-405 30 Göteborg, Sweden. Electronic address: kristina.hedfalk@chem.gu.se.
authors.forename: Kristina
authors.initials: K
authors.lastname: Hedfalk
mesh_terms: D020346:Aquaporins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D020346:Aquaporins
keywords: Aquaporin; Co-precipitation; Membrane protein; Protein–protein interaction; Yeast two-hybrid interaction assay