Answer to Question #243136 in Psychology for Sli

Question

The electrical charge resulting from the difference between the positive and negative ions outside and inside the cell results in...

Answer 1

 I respectfully disagree that phosphatidylserine (PS) distribution is the major contributor to the canonical "inside-negative" membrane potential. Rather, as I understand, the main driver is a series of membrane protein ion-transporters & channels which act in clever unison to establish and maintain an ion gradient across the cell membrane, resulting in a net-negative charge inside the membrane. Specifically we should talk about the Na/K pump (an ATPase) and potassium leak channels.

Here's my brief & incomplete synopsis of what's going on here... First, the Na/K pump utilizes the energy released upon hydrolysis of 1 ATP to drive 3 Na+ ions out of the cell, and two K+ ions into the cell. Both of these movements are "uphill" processes (thus requiring energy from ATP), resulting in an excess of K+ inside the cell and a deficit of Na+. Due to the 3:2 transport stoichiometry, at this point we have a net movement of one positive ion out of the cell, so there's already a net negative charge inside the cell. But wait, the plot thickens! Since there is now an excess of K+ ions inside the cell, they can spontaneously flow down their concentration gradient, out of the cell, through special selective K+ "leak-channels," increasing the magnitude of the net negative charge inside the cell. Eventually, a quite complex state of equilibrium is reached - what we call the resting negative potential. 

From my personal familiarity with membrane protein biochemistry as well as cellular electrophysiology, what I've outlined is the generally accepted "mickey mouse" explanation of the membrane potential. But remember that this process is highly variable across the menagerie of cell types, and is dependent on a very complex set of variables. There are numerous other players and contingencies, and we're only talking about the resting potential here. Things get murkier when we wade into non-equilibrium waters!