ABSTRACT
Computer modeling of the outer hair cell (OHC) motor protein prestin produces ambiguous results regarding transmembrane regions and localization of its termini. To determine the location of prestin's N- and C-termini, we created prestin constructs with synthetic epitopes located immediately upstream or downstream of prestin. The spatial distribution of these epitopes was studied in prestin-transfected cells using immunofluorescence. In permeabilized cells, antibodies label the plasma membrane of 30% of the cells, reflecting transfec- tion efficiency. Under non-permeabilizing conditions, the few labeled cells also displayed a lack of plasma membrane integrity. These data suggest that prestin's N-and C-termini are cytoplasmic. Furthermore, prestin staining in OHCs was observed only under permeabilizing conditions. These results implicate prestin's N- and C-termini as portions that may interact with other cytoplasmic proteins. A model of prestin membrane topology is also considered based on the results.
Subject(s)
Cell Membrane/chemistry , Epitopes/chemistry , Hair Cells, Auditory, Outer/chemistry , Proteins/chemistry , Animals , Antibody Specificity/genetics , Cell Membrane/ultrastructure , Cell Membrane Permeability/drug effects , Cell Membrane Permeability/physiology , DNA, Complementary/genetics , Epitopes/genetics , Fluorescent Antibody Technique , Gerbillinae , Green Fluorescent Proteins , Hair Cells, Auditory, Outer/ultrastructure , Hearing/physiology , Indicators and Reagents/analysis , Luminescent Proteins/analysis , Membrane Potentials/drug effects , Membrane Potentials/physiology , Models, Biological , Protein Structure, Tertiary/physiology , Rabbits , Signal Transduction/physiology , TransfectionABSTRACT
The outer and inner hair cells of the mammalian cochlea perform different functions. In response to changes in membrane potential, the cylindrical outer hair cell rapidly alters its length and stiffness. These mechanical changes, driven by putative molecular motors, are assumed to produce amplification of vibrations in the cochlea that are transduced by inner hair cells. Here we have identified an abundant complementary DNA from a gene, designated Prestin, which is specifically expressed in outer hair cells. Regions of the encoded protein show moderate sequence similarity to pendrin and related sulphate/anion transport proteins. Voltage-induced shape changes can be elicited in cultured human kidney cells that express prestin. The mechanical response of outer hair cells to voltage change is accompanied by a 'gating current', which is manifested as nonlinear capacitance. We also demonstrate this nonlinear capacitance in transfected kidney cells. We conclude that prestin is the motor protein of the cochlear outer hair cell.
Subject(s)
Hair Cells, Auditory, Outer/physiology , Membrane Transport Proteins , Molecular Motor Proteins , Proteins/physiology , Amino Acid Sequence , Animals , Anion Transport Proteins , Biomechanical Phenomena , Carrier Proteins/physiology , Cell Line , Cell Movement , Cloning, Molecular , DNA, Complementary , Electric Conductivity , Gene Expression , Gerbillinae , Hair Cells, Auditory, Outer/chemistry , Humans , Molecular Motor Proteins/drug effects , Molecular Sequence Data , Polymerase Chain Reaction , Proteins/analysis , Proteins/genetics , Sequence Homology, Amino Acid , Sodium Salicylate/pharmacology , Sulfate Transporters , Tissue Distribution , TransfectionABSTRACT
We are developing a networked resource for the National Library of Medicine's Unified Medical Language System. We call this resource the UMLS Retriever, which is an instance of our VNS Retriever architecture. Our prototype user interface makes use of the Virtual Notebook System Browser. The development of a networked UMLS service will result in numerous advantages to our user community.
Subject(s)
Computer Communication Networks , Information Storage and Retrieval , Unified Medical Language System , MEDLARS , User-Computer InterfaceABSTRACT
Baylor College of Medicine has developed the MEDLINE Retriever, a tool to query MEDLINE, the data-base of medical literature at the National Library of Medicine. The MEDLINE Retriever communicates via the Internet to achieve excellent response time for MEDLINE queries. It uses the X Window System and the Motif toolkit, and employs the Knowbot Operating Environment developed by the Corporation for National Research Initiatives. We discuss the architecture of the MEDLINE Retriever, focusing on the graphical user interface that we have developed, as well as our experiences in developing and deploying the MEDLINE Retriever at Baylor. The MEDLINE Retriever is an extension of Baylor's IAIMS design concept that brought forth the Virtual Notebook System, and fits well with Baylor's aims with regard to the High Performance Computing Initiative.
Subject(s)
Information Storage and Retrieval , MEDLINE , Software , Computer Communication Networks , User-Computer InterfaceABSTRACT
During the past several years, Baylor College of Medicine has made a substantial commitment to the use of information technology in support of its corporate and academic programs. The concept of an Integrated Academic Information Management System (IAIMS) has proved central in our planning, and the IAIMS activities that we have undertaken with funding from the National Library of Medicine have proved to be important extensions of our technology development. Here we describe our Virtual Notebook system, a conceptual and technologic framework for task coordination and information management in biomedical work groups. When fully developed and deployed, the Virtual Notebook will improve the functioning of basic and clinical research groups in the college, and it currently serves as a model for the longer-term development of our entire information management environment.