title: GEC1-kappa opioid receptor binding involves hydrophobic interactions: GEC1 has chaperone-like effect.
abstract: We demonstrated previously that the protein GEC1 (glandular epithelial cell 1) bound to the human kappa opioid receptor (hKOPR) and promoted cell surface expression of the receptor by facilitating its trafficking along the secretory pathway. Here we showed that three hKOPR residues (Phe345, Pro346, and Met350) and seven GEC1 residues (Tyr49, Val51, Leu55, Thr56, Val57, Phe60, and Ile64) are indispensable for the interaction. Modeling studies revealed that the interaction was mediated via direct contacts between the kinked hydrophobic fragment in hKOPR C-tail and the curved hydrophobic surface in GEC1 around the S2 beta-strand. Intramolecular Leu44-Tyr109 interaction in GEC1 was important, likely by maintaining its structural integrity. Microtubule binding mediated by the GEC1 N-terminal domain was essential for the GEC1 effect. Expression of GEC1 also increased cell surface levels of the GluR1 subunit and the prostaglandin EP3.f receptor, which have FPXXM and FPXM sequences, respectively. With its widespread distribution in the nervous system and its predominantly hydrophobic interactions, GEC1 may have chaperone-like effects for many cell surface proteins along the biosynthesis pathway.
authors.affiliation: Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Chen
authors.forename: Chongguang
authors.initials: C
authors.lastname: Chen
authors.forename: Evangelia
authors.initials: E
authors.lastname: Kotsikorou
authors.forename: Diane L
authors.initials: DL
authors.lastname: Lynch
authors.forename: Patricia H
authors.initials: PH
authors.lastname: Reggio
authors.forename: Lee-Yuan
authors.initials: LY
authors.lastname: Liu-Chen
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D017433:Protein Structure, Secondary / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D018091:Receptors, AMPA / Q000235:genetics / Q000378:metabolism; D017473:Receptors, Opioid, kappa / Q000235:genetics / Q000378:metabolism*; D018078:Receptors, Prostaglandin E / Q000235:genetics / Q000378:metabolism; D058308:Receptors, Prostaglandin E, EP3 Subtype
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D008869:Microtubule-Associated Proteins; D018832:Molecular Chaperones; D018091:Receptors, AMPA; D017473:Receptors, Opioid, kappa; D018078:Receptors, Prostaglandin E; D058308:Receptors, Prostaglandin E, EP3 Subtype; C430503:GABARAPL1 protein, human; C545647:PTGER3 protein, human