Ubiquitin-like modifier involved in the formation of autophagosomal vacuoles (autophagosomes) (PubMed:26687600). When lipidated mediates tethering between adjacent membranes and stimulates membrane fusion (PubMed:26687600). Less effective at promoting membrane fusion than lgg-1 (PubMed:26687600). Acts upstream of the autophagy protein epg-5 in the aggrephagy pathway, which is the macroautophagic degradation of ubiquitinated protein aggregates, and preferentially interacts with autophagy proteins and substrates containing LIR motifs to mediate autophagosome formation and protein aggregate degradation (PubMed:26687600). In particular binds to components of an atg-5-lgg-3-atg-16 complex to regulate autophagosome formation and cargo sequestration (PubMed:26687600). Required for the degradation of specific sqst-1-containing aggregates during embryogenesis and the early stages of larval development (PubMed:26687600). Involved in allophagy, which is an autophagic process in which paternal mitochondria and organelles are degraded during fertilization, and moreover is required for the degradation of lgg-1-positive allophagic autophagosomes in embryos (PubMed:25126728, PubMed:24374177). Involved in xenophagy, the autophagy-mediated degradation of pathogens and pathogen products, such as toxins (PubMed:27875098). Also plays a role in membrane-pore repair (PubMed:27875098). Through HOPS complex subunit vps-39, tethers lysosomes with autophagosomes to form autolysosomes (PubMed:24374177). Plays a role in the distribution and clearance of germ cell specific P-granules from somatic cells to ensure exclusive localization of the P-granules in germ cells (PubMed:19167332). Essential for dauer development and life-span extension (PubMed:20523114). May interact with vps-39 (PubMed:24374177). Interacts with lgg-3; the interaction is direct (PubMed:26687600). Interacts with atg-16.1 (via WD domain) and atg-16.2 (via WD 5-6 repeats); the interactions are direct (PubMed:26687600). Interacts with sepa-1 (via the LIR motifs); the interaction is direct (PubMed:26687600). Interacts with sqst-1 (via the LIR motifs); the interaction is direct (PubMed:26687600). Interacts with epg-2 (via the LIR motifs); the interaction is weak (PubMed:26687600). Interacts with atg-7; the interaction is direct (PubMed:26687600). Interacts with atg-3 (PubMed:26687600). The interaction with atg-7 and atg-3 may be required for the lipidation of lgg-2 (PubMed:26687600). In embryos, diffuse cytoplasmic localization with some areas displaying a more punctate distribution (PubMed:24374177). Specifically, upon fertilization localizes to autophagosomes around the male pronucleus. During the first embryonic divisions and after the 25-cell stage, localizes to a small population of autophagosomes and to another small population of autophagosomes containing both lgg-1 and lgg-2. Localization to autophagosomes is dependent on atg-7. Expressed during embryogenesis. This protein is subject to lipidation (PubMed:26687600). Lipidation is regulated by lgg-1 (PubMed:26687600). Viable with no visible defects in development or fertility (PubMed:24374177). Embryos contain an increased number of endosomes (PubMed:25126728). Lysosomes have a reduced capacity to interact with autophagosomes in embryos and furthermore, there is defective autophagosome degradation with an accumulation of lgg-1-positive autophagosomes in 500-cell embryos (PubMed:24374177). Double knockout with rab-7 partially rescues the defective lgg-1- and lgg-2-positive autophagosome degradation defect in the individual rab-7 and lgg-2 single mutants (PubMed:24374177). RNAi-mediated knockdown results in the accumulation of germ cell specific P-granules in somatic cells as indicated by increased numbers of pgl-1 positive granules in embryos (PubMed:19167332). RNAi-mediated knockdown reduces autophagic degradation of membrane pore-forming toxin Cry5B. Belongs to the ATG8 family.