Cellular microcompartments constitute general suborganellar functional units in cells

Abstract

All cells are compartmentalized to facilitate enzymatic reactions or cellular dynamics. In eukaryotic cells, organelles differ in their protein/lipid repertoire, luminal ion composition, pH, and redox status. In addition, organelles contain specialized subcompartments even within the same membrane or within its lumen. Moreover, the bacterial plasma membrane reveals a remarkable degree of organization, which is recapitulated in eukaryotic cells and often linked to cell signaling. Finally, protein-based compartments are also known in the bacterial and eukaryotic cytosol. As the organizing principle of such cellular subcompartments is likely similar, previous definitions like rafts, microdomains, and all kinds of ' -somes ' fall short as a general denominator to describe such suborganellar structures. Within this review, we will introduce the term cellular microcompartment as a general suborganellar functional unit and discuss its relevance to understand subcellular organization and function.

CORVET and HOPS tethering complexes–coordinators of endosome and lysosome fusion

“…As several hydrolases require transmembrane receptors for their targeting to endosomes and lysosomes, these receptors need to be sorted back to the Golgi. It can thus be hypothesized that MVBs only fuse efficiently with lysosomes if, first, recycling of sorting receptors has been completed and, second, all ubiquitylated receptors have been cleared off from the endosomal surface by ESCRTs (Epp et al, 2011;Holthuis and Ungermann, 2013). In addition to endosomal fusion with lysosomes, at least two other fusion events take place at the yeast vacuole.…”

Mitochondrial Band-7 family proteins: scaffolds for respiratory chain assembly?

“…Biological membranes are highly organized proteolipid domains and there is increasing evidence of fine-scale organization into microdomains (Whitelegge, 2011; Holthuis and Ungermann, 2013). These comprise localized assemblies of specific proteins and lipids and are important in the spatial and temporal control of membrane protein complex assembly and regulation.…”

Three-dimensional Organization of Layered Apical Cytoskeletal Networks Associated with Mouse Airway Tissue Development

“…During epithelial cell polarization, various types of cytoskeleton, including actin filaments, intermediate filaments, and microtubules, play specific roles. In addition, the formation of subcellular compartments, highly specialized cellular regions which are indispensable for development4, coincide with typical structures containing multiple cytoskeletons, such as the midbody in dividing cells and the leading edge in migrating cells56. Although these cytoskeletal “superstructures” are involved in sophisticated cellular functions, high-resolution and three-dimensional information revealing their organization, including their changes during tissue maturation, is still fragmentary.…”