title: Heterodimerization with the β1subunit directs the α2subunit of nitric oxide-sensitive guanylyl cyclase to calcium-insensitive cell-cell contacts in HEK293 cells: Interaction with Lin7a.
abstract: Nitric oxide-sensitive guanylyl cyclase is a heterodimeric enzyme consisting of an α and a β subunit. Two different α subunits (α1and α2) give rise to two heterodimeric enzymes α1/β1and α2/β1. Both coexist in a wide range of tissues including blood vessels and the lung, but expression of the α2/β1form is generally much lower and approaches levels similar to the α1/β1form in the brain only. In the present paper, we show that the α2/β1form interacts with Lin7a in mouse brain synaptosomes based on co-precipitation analysis. In HEK293 cells, we found that the overexpressed α2/β1form, but not the α1/β1form is directed to calcium-insensitive cell-cell contacts. The isolated PDZ binding motif of an amino-terminally truncated α2subunit was sufficient for cell-cell contact localization. For the full length α2subunit with the PDZ binding motif this was only the case in the heterodimer configuration with the β1subunit, but not as isolated α2subunit. We conclude that the PDZ binding motif of the α2subunit is only accessible in the heterodimer conformation of the mature nitric oxide-sensitive enzyme. Interaction with Lin7a, a small scaffold protein important for synaptic function and cell polarity, can direct this complex to nectin based cell-cell contacts via MPP3 in HEK293 cells. We conclude that heterodimerization is a prerequisite for further protein-protein interactions that direct the α2/β1form to strategic sites of the cell membrane with adjacent neighbouring cells. Drugs increasing the nitric oxide-sensitivity of this specific form may be particularly effective.
authors: Department of Pharmacology, Toxicology and Clinical Pharmacy, University of Braunschweig - Institute of Technology, Germany. Electronic address: j.hochheiser@tu-braunschweig.de.
authors: Julia
authors: J
authors: Hochheiser
authors: Department of Pharmacology, Toxicology and Clinical Pharmacy, University of Braunschweig - Institute of Technology, Germany. Electronic address: tobias_haase@hotmail.com.
authors: Tobias
authors: T
authors: Haase
authors: Department of Pharmacology, Toxicology and Clinical Pharmacy, University of Braunschweig - Institute of Technology, Germany. Electronic address: mareike.busker@gmx.de.
authors: Mareike
authors: M
authors: Busker
authors: Department of Pharmacology, Toxicology and Clinical Pharmacy, University of Braunschweig - Institute of Technology, Germany. Electronic address: a.soemmer@tu-braunschweig.de.
authors: Anne
authors: A
authors: Sömmer
authors: Institute for Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. Electronic address: kreienkamp@uke.de.
authors: Hans-Jürgen
authors: HJ
authors: Kreienkamp
authors: Department of Pharmacology, Toxicology and Clinical Pharmacy, University of Braunschweig - Institute of Technology, Germany. Electronic address: s.behrends@tu-braunschweig.de.
authors: Sönke
authors: S
authors: Behrends
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D057809:HEK293 Cells; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009569:Nitric Oxide; D021122:Protein Subunits; D021381:Protein Transport / Q000502:physiology; D000071756:Soluble Guanylyl Cyclase / Q000378:metabolism*; D033921:Vesicular Transport Proteins
chemical_list: C486532:LIN7A protein, human; D008565:Membrane Proteins; D021122:Protein Subunits; D033921:Vesicular Transport Proteins; D009569:Nitric Oxide; D000071756:Soluble Guanylyl Cyclase; D002118:Calcium
keywords: Cyclic GMP; Guanylyl cyclase; Nitric oxide; PDZ domain