How to prepare for your annual encounter with confusion. Daylight Saving Time ends Sunday at 2 a.m., which means that weâre all going to spend a few minutes scratching our heads trying to figure out whether weâre gaining or losing an hour of sleep. Save yourself the trouble and let TIME break it down for you.
For example, plasma membrane proteins carry out functions as diverse as ferrying nutrients across the plasma membrane, receiving chemical signals from outside the cell, translating chemical signals into intracellular action, and sometimes anchoring the cell in a particular location (Figure 4).
These proteins, called peripheral membrane proteins, are only associated with one side of the membrane or the other-never both. Only the transmembrane proteins can operate on both sides of the membrane at once, and they often serve to signal events taking place outside the cell, to vital functions inside the cell. They also serve as exits and entrances, transporting vital materials from one side of the membrane to the other.