Final answer:
Lysosomal enzymes are specifically tagged with a mannose 6-phosphate (M6P) tag in the trans Golgi network. This M6P tag enables them to be recognized and sorted into clathrin-coated vesicles for transport to the lysosome where they aid in degradation processes.
Step-by-step explanation:
The molecular tag that selects cargo proteins for the lysosome is called a mannose 6-phosphate (M6P) tag. Proteins destined for the lysosome are typically tagged with M6P in the trans Golgi network. This tagging helps in sorting and directing the proteins to lysosomes where they perform their function in degradation and recycling of cellular waste.
During the synthesis and processing of lysosomal enzymes, they receive a phosphate group on their mannose residues, resulting in the M6P tag. This process occurs in the cis and medial sections of the Golgi apparatus. The M6P tag is recognized by M6P receptors in the trans Golgi network, which ensures the lysosomal enzymes are packed into clathrin-coated vesicles.
The vesicles then bud off and are transferred to endosomes. Endosomes mature into lysosomes where the low pH environment triggers the dissociation of the M6P receptors from the enzymes, leaving the enzymes to function in the lysosome. Through this process, cells maintain a proper distribution and functioning of enzymes responsible for degrading biomolecules.