During neural development, outgrowing
nerve cell axons must interact with their cellular environment in
order to determine correct organization and connectivity. Cell
adhesion molecules (CAMs) are prominent one pass
transmembrane glycoproteins that mediate the signaling
necessary to ensure correct targeting of these nerve axons.

a) How is a cell adhesion
transmembrane protein sorted/translocated
initially so that it will be inserted into the plasma membrane as a
type I membrane protein? [Hint: Describe the
specific steps that a type I transmembrane protein will go through
in the RER for insertion into the membrane].

b) The binding of cell surface
receptor to its ligand is the 1^st step in a signal
transduction pathway which ultimately results in the activation of
many cytoplasmic proteins in a step-wise fashion. Explain 2
reasons why this method of signaling is advantageous for a
cell.