We considered a cytoplasmic compartment, in which WIPI1/2, LC3-I and mature AVs are found, and a membrane-of-origin compartment, from which all PGs emerge.
By comparison to haematopoietic cells (Fig 1G, Cells), which reveal a ∼25% Ch and ∼9% SM content of the total lipid composition, the prominin-1-immunoprecipitated vesicle fraction (Fig 1G, prominin-1-CMV) appears enriched in Ch and SM with ∼37 and ∼19%, respectively, thus indicating a distinct lipidic composition compared to the membranes of origin.
A final difficulty with saltatory hypotheses involving host membrane rupture and resealing is that the mitochondrial inner membrane is likely of bacterial origin and the outer membrane of host origin (see below).
In our hypothesis, however, the originally internalized proto-mitochondrion would be surrounded by an inner membrane of bacterial origin and an outer membrane of host origin, each oriented such that their membrane pumps would maintain a high Na, low K inter-membrane environment.
In parallel with the growth of the haustorium, the host cell generates a membrane of unknown origin, which surrounds the haustorium.
We suggest that this fraction might be the equivalent of the mitochondria associated membrane of ER origin that delivers phospholipids to the mitochondria, and to the recently isolated ER-derived membrane fraction that is in close contact with chloroplasts.
Arbuscules remain surrounded by a membrane of plant origin, called the periarbuscular membrane (PAM), hosting specific transporters like the phosphate transporter MtPt4 [ 50] or the recently identified ABC-transporters MtStr and MtStr2 [ 51].
This enhanced metabolic capability is predicted to contribute to the lipid requirement of Portiera, which has no capacity for lipid biogenesis, and the synthesis of the symbiosome membrane of insect origin that bounds each bacterial cell within the bacteriocyte.
After grafting, a biodegradable collagen membrane of porcine origin (Bio-Gide®, Geistlich AG, Wolhusen, Switzerland) was trimmed and adapted over the NBM using a double-layer technique to retard the resorption of the barrier [ 3] (Fig. 5).
When a viable malaria parasite productively invades a hepatocyte, it surrounds itself with a membrane of hepatocyte origin, called the PVM, which is subsequently modified by the LS parasite.
During infection by diverse viral families, RNA replication occurs on the surface of virally induced cytoplasmic membranes of cellular origin.
