The Ion Channels and the Malfunction in the Cells 

UNIVERSIDAD NACIONAL AUTÓNOMA DE MÉXICO 

ENP 6 "ANTONIO CASO"

TEAM: 

• Cabrera Meza Ana Paulina
• Fuentes Lugo Omar
• Gudiño Guzmán Ana Karen
• Huitrón Loma Jaime Ricardo

TEACHERS:

• María Mercedes Camacho Reyes
• María Josefina Segura Gortares

Objetives

The student knows about ion channels, its function and its usefulness within the cell as well as the causes that might affect them and get to spoil their optimal functioning.

Introduction:

In this blog we will talk about a topic on biology. It is Ionic Channels. Discuss topics such as What are Ionic Channels? What is its significance? Where is? and What is its function?

Implement by some documents extracted from the DGB (General Directorate of Libraries) of the Autonomous National University of Mexico well as some videos that can help you better understand the meaning of what the Ion Channels.

Porpuse

The reason why this topic has been chosen for the key parts in the cell cycle process. This space is just for educational purposes and can help other people in relation to the subject.

Materials

To make this work the following resources were used:

• Google (search engine)

• Youtube

• Articles of DBG

 What is an ion channel?

 Ion channels are water-filled, biological “sub-nanotubes” formed by large protein

molecules. They constitute a class of membrane proteins that serve as conduits for

rapid, regulated ion movement across cellular membranes

Where are the ion channels located?

Located in the plasma membrane.

How does the ion channels work?

The channels are proteins embedded in cell membranes . Note that not only found in the outer membranes , but which also exist in other membranes , such as the endoplasmic reticulum and mitochondria.

The chain of the protein ( α subunit, β , etc.). Repeatedly crosses the membrane and expands the cell cytoplasm and outside the cell. The chain fragment that crosses the membrane domain is called α and is always a string. Each domain can have one or more transmembrane segments which are portions included in the cell membrane. There is often a charge of ion selectivity and opening of the channel pore intramembrane loop ( H5, hairpin ) . This part of the protein outside the cell and inside the cell part . The outside of polysaccharides can join .

Typically the channel is formed by several different protein subunits called , which are called α , β , etc . A channel is formed by combinations of these units form dimers, trimers or tetramers . Normally any subunit alone can form a functional channel, but the addition of the remaining subunits improvements or changes the operation of the canal.

At several subunits together form a circular structure leaving a pore in the center through which pass ions . If the channel is voltage - sensitive, has a protein fragment ( hairpin ) consisting of amino acids can be ionized , usually included in the membrane, which is sensitive to voltage and open or close the channel as a gate . If the channel depends on a ligand to open or close , is a place where this can join.

There may be a portion of the intracellular amino acid chain to function as a shutter covering or uncovering the channel pore .

It is also usually a part that facilitates union with other units α or β . The three-dimensional structure ( topology) and polar characteristics of the amino acids of these protein units are those that determine the functional properties of the channels.

Why couldn't the ion channels work?

How are conditions of ion channels work?

What causes the failure of ion channels?

Summary "Topics in medicinal chemestry"

Ion channels are membrane protein complexes allowing the passive flow of ions across biological membranes. The majority of ion channels possess a pore loop, a region of the protein that repeatedly crosses the membrane to form the selectivity filter that discriminates among ion species. By regulating ion fluxes, ion channels govern membrane potential and excitability, determine the shape of the action potential, trigger muscle contraction and exocytosis (through Ca2+ influx), keep cell volume under control and are involved in many other cellular processes. Therefore, we can conclude that due to their important functional roles, their membrane location, structural heterogeneity and the specific tissue expression of some channel types, ion channels represent interesting targets for drug discovery.

Sodium Channels: Their Structure and Functions, Diseases
Related to Na-Channels

VGSCs are a family of membrane proteins forming a pore, through which they selectively conduct sodium ions inward and outward cell’s plasma membranes in response to variations of membrane potentials. Toxin bindings on the external pore, mutational analysis and parallel studies carried on for voltage-gated potassium channels suggest that the four S5–S6 linkers, one from each domain, which are designed as P-loops, form the extracellular portion of the channel, a ring of suitable size and charge that works as the selectivity filter for sodium ions.

2.2 VGSC Functions

The primary role of VGSCs is to trigger the rising phase of action potential in most excitable cells in mammals. The transition from a resting state, when the channel is closed, to an active state, when the channel is open and Na+ ions can enter the pore, is called gating . In the case of VGSCs, gating is governed by voltage signals. The highly conserved S4 transmembrane segments contain a motif of three positively charged amino acids, which are exposed to the intracellular surface in the resting state and move outwardly in response to depolarization.

Immunohistochemical studies revealed a highly conserved intracellular loop connecting domains III and IV of the a-subunit. Mutagenesis experiments suggest that a hydrophobic triad of amino acids (isoleucine, phenylalanine, and methionine) present in the loop, which is called IFM motif, play a crucial role in fast inactivation by closing the intracellular entrance of the conductive pore. Moreover, the C terminus of the a-subunit is likely to take part in the stabilization of the inactivated state.

Summary "Biological Membrane Ion Channels"

Biologists have long recognized that the transport of ions and of neutral species across cell membranes is central to physiological function. Specialized molecules, essentially biological nanodevices, have evolved to selectively control. There have to be at least two distinct modes of transport.
Two types of molecules are immediate candidates for control transmembrane flux of ions. Nature could have designed specialized carrier molecules, which first bind ions of other lipophobic species at the water- membrane interface and then diffuse across the membrane. Alternatively, transport could be carried out by channel- forming molecules whose water- filled interiors from electrical shunts.

Summary "Ion channels are transmembrane proteins which contain aqueous pores that when opened allow the selective passage of specific ions across cell membranes."

Ion channels are transmembrane proteins which contain aqueous pores that when opened allow the selective passage of specific ions across cell membranes. Thus, the ion channels are proteins that control the passage of ions, and therefore the electrochemical gradient across the membrane of all living cells. These channels act as gates that open or close depending on external stimuli, although some toxic substances can deactivate their natural function. In mammals, ion channels, determine important processes such as the excitation of the nerve and muscle, the secretion of hormones and neurotransmitters, sensory transduction, control of fluid and electrolyte balance, blood pressure regulation, cell proliferation and processes of learning and memory.

Project developed with the collaboration of:

• Cabrera Meza Ana Paulina
• Fuentes Lugo Omar
• Gudiño Guzmán Ana Karen
• Huitrón Loma Jaime Ricardo