membraankieven

Membraankieven is a term that appears in some Dutch-language discussions of membrane biology to describe membranous substructures thought to function as selective sieves within or across cellular membranes. The word combines membraan (membrane) and kieven (to sieve), reflecting a proposed role in regulating which molecules pass through a membrane.

In its usage, membraankieven are described as membrane-bound or closely associated compartments that may possess pore-like or mesh-like features capable of restricting diffusion by size, charge, or conformation. They are sometimes positioned as part of the broader endomembrane system or as interfaces between cells and their environment. The concept emphasizes sieve-like selectivity as a mechanism distinct from classical transport channels or carrier proteins, though in practice many discussions treat membraankieven as a descriptive metaphor for specialized transport complexes.

Structure and function are generally described as hypothetical or preliminary, with proposed characteristics including a lipid bilayer enclosure, a surrounding protein mesh or pores, and regulatory domains responsive to signaling molecules. The exact molecular composition, biogenesis, and regulatory pathways of membraankieven remain unsettled in the literature, and there is no widespread, universally accepted definition or classification.

Occurrence and status in the literature are limited. The term has appeared in a small number of niche articles and reviews, and it is not widely adopted as a standard category in mainstream cell biology. Researchers emphasize the need for clearer criteria, rigorous characterization, and consensus before membraankieven can be integrated as a recognized component of cellular transport systems.

See also: membrane transport, pore, vesicle, endosome, transport protein.