Fig. 7.

Model for the involvement of COPII (blue) and COPI (green) in ATGL transport to LDs. ATGL associates with ER membranes and is subsequently transported to specialized ERES and ERGIC structures that are adjacent to pre-existing LDs. ATGL then co-segregates with neutral lipids into nascent LDs, which subsequently fuse with larger LDs. It is also possible that a transfer protein translocates ATGL from an ERGIC domain to LDs. Steps in this process are enabled by sequential action of SAR1-COPII and GBF1-ARF1-COPI.