Endocytosis in Nature Reviews Molecular Cell Biology
Nature Reviews Molecular Cell Biology (doi:10.1038) has an edition devoted to endocytosis. There is a nice little introduction to the topic at the website. It notes that endocytosis is associated with numerous functions. These functions include cell adhesion and migration, receptor signalling, nutrient uptake, pathogen entry and cell polarity. Extracellular molecules absorbed through endocytic membrane trafficking need to undergo a sorting process. As stated the different "endocytic processes can be distinguished by the size of the vesicle formed, their cargo and the machineries involved." Origin of life theories often refer to the tendency of lipids to self-assemble as evidence for some kind of ancient proto-cell membrane; one apparently lacking trafficking functions. The linked article notes that "selection of cargo by adaptor proteins is considerably more complex than initially anticipated." Is this the type of process that nature can forego entirely or even tolerate at some sort of very suboptimal level? Maybe, but it looks like the kind of topic a science fiction writer should develop.