p62/SQSTM1

Autophagy is an important cellular process that maintains homeostasis by degrading and recycling damaged proteins and organelles. Autophagy receptors, such as p62/SQSTM1, recognize these intracellular cargo and mediate their engulfment by the double-membrane autophagosome. The autophagosomes are subsequently targeted to the lysosome for degradation. An early regulatory step in this process is the activation and lipidation of ATG8 related proteins such as microtubule-associated protein-1 light chain 3 (LC3).

During autophagy ubiquitinated cargo or substrates are engulfed in a double-membrane autophagosome and transported to the lysosome for degradation. This process is important for maintaining cellular homeostasis and for degrading damaged organelles or misfolded protein aggregates. p62, also known as sequestosome 1 (SQSTM1), is an autophagy receptor that recognizes and recruits cargo to the autophagosome through its interaction with Atg8.

Microtubule-associated protein-1 light chain 3 (LC3/LC3B) is a ubiquitin-like protein involved in the formation of the autophagosome. It is homologous to the yeast Atg8 protein. Autophagosomes are important for the degradation and recycling of intracellular cargo such as misfolded proteins or damaged organelles. Upon induction of autophagy, LC3 is conjugated to the lipid phosphatidylethanolamine (PE) by the Atg12-Atg5-Atg16 protein complex.

p62/SQSTM1 (sequestosome 1) is ubiquitously-expressed cytoplasmic/adaptor protein. SQSTM1 functions as a signaling hub for various signal transduction pathways involved in apoptosis, cell differentiation, apoptosis, immune response, and K+ channel regulation. It is conserved in vertebrates and can be induced by a wide variety of triggers including the proteasomal inhibitor PSI, PGJ2/prostaglandin J2, and the tumor promoting agent phorbol 12-myristate 13-acetate (PMA).