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intrinsic protein
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Detailed diagram of a plasma membrane's lipid bilayer showing two layers of phospholipid molecules with hydrophilic heads facing outward and hydrophobic tails inward, embedded cholesterol, integral (intrinsic) proteins spanning the membrane, peripheral (extrinsic) proteins attached to the surface, and sugar side chains extending from the outer face.
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intrinsic protein

biology
Also known as: integral protein
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Detailed diagram of a plasma membrane's lipid bilayer showing two layers of phospholipid molecules with hydrophilic heads facing outward and hydrophobic tails inward, embedded cholesterol, integral (intrinsic) proteins spanning the membrane, peripheral (extrinsic) proteins attached to the surface, and sugar side chains extending from the outer face.
Molecular view of the cell membrane Intrinsic proteins penetrate and bind tightly to the lipid bilayer, which is made up largely of phospholipids and cholesterol and which typically is between 4 and 10 nanometers (nm; 1 nm = 10−9 metre) in thickness. Extrinsic proteins are loosely bound to the hydrophilic (polar) surfaces, which face the watery medium both inside and outside the cell. Some intrinsic proteins present sugar side chains on the cell's outer surface.

Intrinsic proteins are a type of protein firmly embedded within the phospholipid bilayer of cell membranes. These proteins, along with extrinsic proteins, make up the cell membrane, which acts as a barrier between the cell and its environment, controlling the passage of substances.1

Intrinsic membrane proteins often have specific amino acid sequences that allow them to span the cell membrane. They play crucial roles in various cellular functions, and their specific types vary depending on the membrane's physiological purpose. Some intrinsic proteins are involved in cell signaling, and defects in their structure can lead to conditions like cancer.12

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2 Britannica Sources
  1. cell - Membrane proteins
  2. lipid - Physical characteristics of membranes

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