FunctionUbiquitin-like modifier that increases cell-surface expression of kappa-type opioid receptor through facilitating anterograde intracellular trafficking of the receptor. Involved in formation of autophagosomal vacuoles. Whereas LC3s are involved in elongation of the phagophore membrane, the GABARAP/GATE-16 subfamily is essential for a later stage in autophagosome maturation.
Tissue specificityUbiquitous. Expressed at very high levels in the brain, heart, peripheral blood leukocytes, liver, kidney, placenta and skeletal muscle. Expressed at very low levels in thymus and small intestine. In the brain, expression is particularly intense in motoneurons in the embryo and in neurons involved in somatomotor and neuroendocrine functions in the adult, particularly in the substantia nigra pars compacta.
Sequence similaritiesBelongs to the ATG8 family.
Post-translational modificationsThe precursor molecule is cleaved by ATG4B to form the cytosolic form, GABARAPL1-I. This is activated by APG7L/ATG7, transferred to ATG3 and conjugated to phospholipid to form the membrane-bound form, GABARAPL1-II (By similarity). ATG4B also mediates the delipidation required for GABARAPL1 recycling when autophagosomes fuse with lysosomes. The Legionella effector RavZ is a deconjugating enzyme that produces an ATG8 product that would be resistant to reconjugation by the host machinery due to the cleavage of the reactive C-terminal glycine.