In a neuron,ion channels are made of $.....P....$ and are located in $.....Q.....$.
$\quad\quad P\quad\quad Q$

• A
  Carbohydrates $\quad$ Cytoplasm
• B
  Carbohydrates $\quad$ Neural membrane
• C
  Proteins $\quad$ Cytoplasm
• D
  Proteins $\quad$ Neural membrane