Membraanivalkudel

Membraanivalkudel, known in English as membrane proteins, are proteins that are embedded within or associated with biological membranes. These proteins play a crucial role in cellular function by facilitating transport across the membrane, acting as receptors for signals, and participating in cell adhesion and recognition. They are integral to the structure and function of all cell membranes, including the plasma membrane and the membranes of organelles.

Membrane proteins can be broadly classified into two main categories: integral membrane proteins and peripheral membrane proteins. Integral membrane proteins are permanently attached to the lipid bilayer and can only be removed by disrupting the membrane, often through the use of detergents. They typically span the entire membrane, with portions exposed to both the interior and exterior of the cell, or they may be embedded within one leaflet of the bilayer. Peripheral membrane proteins, on the other hand, are temporarily associated with the membrane surface or with integral membrane proteins. They can be detached by changes in pH, salt concentration, or the addition of chelating agents, without disrupting the lipid bilayer.

The diverse functions of membrane proteins include acting as channels and transporters for ions and small molecules, enzymes that catalyze reactions at the membrane surface, receptors that bind to signaling molecules and initiate intracellular cascades, and structural proteins that maintain cell shape and connect the cell to its environment. Their proper functioning is essential for cellular homeostasis and organismal health, and dysfunctions in membrane proteins are implicated in numerous diseases.