Cell surface receptors — Which set correctly belongs to the category of plasma membrane receptors?

Introduction:
Cells deploy multiple classes of receptors at the plasma membrane to detect and transduce extracellular signals. This question reviews which families are considered cell surface receptors.

Given Data / Assumptions:

• Receptors can be located at the cell surface or inside the cell.
• Each listed class has characteristic mechanisms of action.
• We are categorizing by location (surface) rather than ligand type.

Concept / Approach:
Enzyme linked receptors (e.g., receptor tyrosine kinases), ion channel linked receptors (ligand gated channels), and G protein coupled receptors are all embedded in the plasma membrane and initiate signaling upon ligand binding.

Step-by-Step Solution:

Verification / Alternative check:
Biochemistry texts consistently group these three under cell surface receptor classes, in contrast to intracellular nuclear receptors that bind lipophilic ligands.

Why Other Options Are Wrong:

• Any single class alone is incomplete given the question asks which come under the category.
• Nuclear receptors: intracellular, not cell surface.

Common Pitfalls:
Mixing location categories with signaling mechanism categories. Here, location at the plasma membrane defines cell surface receptors.

Final Answer:
All of these.