BIOL 2P03 Lecture Notes - Lecture 14: Intermediate Filament, Nuclear Membrane, Microfilament
5 Mar 2016
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Intermediate thickness compared to microfilaments (thinnest) and microtubules (thickest) Also line inner nuclear envelope: made up of many different types of fundamental subunits, much more diverse than microfilaments and microtubules, often expressed in tissue-specific manner. Subunits do not bind to nucleotides: no known nucleating or capping proteins, no known motor proteins associated with intermediate filaments. There are many different types of subunits that can assemble into intermediate filaments. The way in which these subunits assemble is very similar though. Four protofibrils associate to form an intermediate filament. Intermediate filaments are much more stable than microfilaments and microtubules. However, subunits can be added to or removed from existing intermediate filaments. In general, disassembly is promoted by phosphorylation of intermediate filaments via protein kinases and reassembly is promoted by dephosphorylation via protein phosphatases. Present within the nucleus of almost all animal and plant cells.
