Under these conditions, some molecules are packaged into COPII vesicles indicating that they are degraded after their retrieval from the Golgi apparatus [16].
Proteins remain because they express signals that prevent them from leaving the ER or promote their retrieval from the Golgi apparatus.
The cargo-selective complex is a trimer of vacuolar protein sorting (Vps) proteins VPS35, VPS29, and VPS26 that sorts cargos into tubules for retrieval to the Golgi apparatus.
To this end, they must possess specific ER localization determinants to prevent their exit from the ER, and/or to interact with receptors responsible for their retrieval from the Golgi apparatus.
Apart from ensuring correct multimeric organization (addressed in more detail later), retrieval from the Golgi apparatus is also important for many ER proteins to retain their strict localization in the ER [ 4].
The human CES2 C-terminal tetrapeptide sequence, His-Thr-Glu-Leu (HTEL), functions in protein retrieval from the Golgi apparatus and in CES retention in the ER lumen [ 12], but this is missing in opossum CES2.1 which may then influence the subcellular location and metabolic role for this enzyme in opossum liver.
It is well documented that soluble ER-resident proteins bear at their C-terminal end a H/KDEL tetrapeptide that ensure their retrieval from the Golgi apparatus to the ER when they escape to this organelle [ 3, 5, 9] via the binding to a receptor named ERD2-like [ 53- 56] located throughout Golgi and in the ER [ 57, 58].
Besides genetic effects, a variety of environmental factors influencing spatial learning and retrieval could be explored in our apparatus by manipulating either the source of information (e.g., investigating the use of multiple potentially conflicting cues; [63]), either the experience of tested individuals (e.g., investigating aging or addiction-related effects; [64], [65]).
Retromer is a protein assembly that plays a central role in orchestrating export of transmembrane-spanning cargo proteins from endosomes into retrieval pathways destined for the Golgi apparatus and the plasma membrane [ 1].
The enrichment in the RR and KK motifs in proteins with greater than one transmembrane domain when compared to the XDEL motif, which is enriched in proteins with no membrane domains, is as expected, since the XDEL motif mediates the retrieval of luminal ER proteins from the Golgi apparatus lumen proteins.
