U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 Immunity and Disease Prevention Research: Davis, CA
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                People

                    Staff Listing
                                    Careers


        


                    Laboratories
                        Stephensen Group
                                    Kable Group
                                    Lemay GroupSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Pacific West Area Davis, California Western Human Nutrition Research Center Immunity and Disease Prevention Research Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            Huang, Lipingitem
                                            Kirschke, Catherine
  Submitted to: FEBS Journal
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 5/31/2007
                                    Publication  Date: 6/11/2007
                                    Citation: Huang, L., Kirschke, C.P. A di-leucine sorting signal in zip1 (slc39a1) mediates endocytosis of the protein. FEDERATION OF EUROPEAN BIOCHEMICAL SOCIETY, 274: 3986-3997, 2007.Interpretive Summary: Zinc can not be translocated across the cell membrane by passive diffusion. Therefore, specialized mechanisms are required for transporting zinc across the plasma membrane and distributing zinc around the cell. Most of members of the ZIP family of zinc transporters function to take up zinc into the cell. It has been demonstrated that the amount of cell membrane expressed ZIP1 is regulated by endocytic mechanisms. In zinc-adequate conditions, the level of surface expressed ZIP1 was low due to the rapid internalization of ZIP1 from the cell membrane. The aim of the present work was to identify signal(s) in the ZIP1 protein that mediated the internalization of ZIP1. Four potential signals including three di-leucine-based and one tyrosine-based sorting signals were found in ZIP1 from a search for functional motifs using the ELM server (http://elm.eu.org). Site-directed mutational analyses and immunofluorescence microscopic assays demonstrated that a di-leucine-based sorting signal, ETRALL144-149, located in the variable loop region between transmembrane domain III and IV of ZIP1 was important for the ZIP1 internalization. Substitutions of alanines for the di-leucine residues (LL148, 149/AA) severely impaired the internalization of ZIP1 from the cell surface and subsequent protein degradation leading to accumulation of the mutant ZIP1 on the cell surface as well as inside the cell. Our results also suggest that this di-leucine sorting signal is required for zinc-induced internalization of ZIP1. In conclusion, the regulatory mechanism of constitutive and zinc-induced internalization and subsequent degradation of ZIP1 is falling into the classical adaptor complex (AP)-mediated endocytic pathway.
                                Technical Abstract: It has been demonstrated that the plasma membrane expression of ZIP1 was regulated by endocytic mechanisms. In zinc-replete conditions, the level of surface expressed ZIP1 was low due to the rapid internalization of ZIP1 from the cytoplasmic membrane. The aim of the present work was to identify sorting signal(s) in the ZIP1 protein that mediated the endocytosis of ZIP1. Four potential sorting signals including three di-leucine-based and one tyrosine-based sorting signals were found in ZIP1 from a search for functional motifs using the ELM server (http://elm.eu.org). Site-directed mutagenesis and immunofluorescence microscopic analyses demonstrated that a di-leucine-based sorting signal, ETRALL144-149, located in the variable loop region between transmembrane domain III and IV of ZIP1 was important for the ZIP1 internalization. Substitutions of alanines for the di-leucine residues (LL148, 149/AA) severely impaired the internalization of ZIP1 from the cell surface and subsequent protein degradation leading to accumulation of the mutant ZIP1 on the cell surface as well as inside the cell. Our results also suggest that this di-leucine sorting signal is required for zinc-induced endocytosis of ZIP1. In conclusion, the regulatory mechanism of constitutive and zinc-induced internalization and subsequent degradation of ZIP1 is falling into the classical adaptor complex (AP)-mediated endocytic pathway.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov