Most vesicles leaving the trans-Golgi cisternae are coated with a protein called a coatomer. This is required to allow the formation of the vesicle. However this protein actually masks the specific targeting protein, that is a long helical protein called a SNARE. SNAREs bring the transpo vesicle from the Golgi close to the specific target membrane so that the two can fuse. The SNARE on the transpo vesicle produced by the Golgi is called a v-SNARE; the one on the target membrane is a t-SNARE. Reference: Harper; 30th edition