intermediate filament

initialism: IF

https://doi.org/10.1351/goldbook.10858

Any of a group of fibrous proteins (including keratin fibres, neurofilaments, desmin, and vimentin) that make up part of the cytoskeleton of most eukaryotic cells; so named because, at about \(\pu{10 nm}\) diameter, they are intermediate in thickness between actin filaments and microtubules.

Note: Most types of intermediate filaments are cytoplasmic, but one type, the lamins, is nuclear.

Source:
PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 769 (https://doi.org/10.1515/pac-2015-1202)