Final answer:
GRABs is the protein family not involved in directing transport vesicles to the target membrane whereas tethering proteins, SNAREs, and Rab GTPases all play roles in vesicle transport and fusion.
Step-by-step explanation:
The protein family that is not involved in directing transport vesicles to the target membrane is A) GRABs. B) Tethering proteins, C) SNAREs, and D) Rab GTPases are all involved in the transport of vesicles within the cell. Tethering proteins are involved in the initial docking of vesicles to the target membrane, the SNAREs (both v-SNAREs on vesicles and t-SNAREs on target membranes) facilitate membrane fusion, and Rab GTPases regulate vesicle trafficking.