Lecture 6 Flashcards
Intermediate filament subunits differ from Microtubules and Microfilaments in that they are ____ rather than globular.
FIBROUS
All 5 types of IFs have the same alpha-helical region consisting of about 310 AAs, but the subunits differ in the size and sequence of their ____ and ____ termini.
AMINO and CARBOXY termini
IFs are long, unbranched structures about ___nm in diameter.
10nm
IF monomer subunits pair to form ____, which line up side by side (staggered) to form _____, which bind end to end to form _____. The final filament is composed of 8 tetramers to form a rope-like filament, which is stronger than MFs and MTs.
Monomers pair to form DIMERS, which line up side by side (staggered) to form TETRAMERS, which bind end to end to form PROTOFILAMENTS. The final filament is composed of 8 tetramers
Type I and II IFs are ____-keratins and ____- keratins respectively, and are predominant types occurring in various _____ and _____-derived cells.
ACID and BASE-keratins respectively, and are predominant types in various EPITHELIAL and EPITHELIAL-derived cells.
There are 5 subclasses of Type III IFs, one of which is Peripherin, found in neurons of _____ nervous system.
Found in neurons of PERIPHERAL nervous system.
Type IV IFs are ____filament proteins
NEUROfilament
Type V IFs are nuclear _____, and are present in all cells.
Nuclear LAMINS
IF associated proteins (IFAPs) cross-link IFs with one another and also with ____ and ____.
MFs and MTs
The main IFAP is ____.
PLECTIN
All cells have nuclear lamin (Type ___ IF), but will have different cytoplasmic IF types depending on the cell type.
All have nuclear lamin (Type V), but will have different cytoplasmic IF types depending on the cell type.
IFs are important in providing mechanical support , help maintain cell adhesion via _____ associated with desmosomes, aid in ____ repair (keratin), and stabilize _____ (desmin.)
Help maintain cell adhesion via KERATIN associated with desmosomes, aid in WOUND repair (keratin), and stabilize SARCOMERES (desmin.)
Nuclear lamins are located along the inner nuclear _____ and less so in the nucleoplasm.
Inner nuclear MEMBRANE
There are 5 key proteins associated with the Nucleoskeleton (LAMSE):
- ____ A and B
- ____
- ____
- ____
- ____
- LAMINS A and B
- ACTIN
- MYOSIN
- SPECTRIN
- EMERIN
Lamins mainly contribute to stability and _____ of nuclear envelope, but are also involved in chromatin organization, transcription, replication, differentiation, and signaling.
Mainly contribute to stability and STIFFNESS
Actin plays a role in establishing and maintaining nuclear _____, and it can be found in 3 forms in the nucleus:
- _____
- _____ filaments that interact with nuclear lamina and other members of nucleoskeleton
- _____
Establishing nuclear STRUCTURE
- MONOMERIC
- SHORT filaments that interact with nuclear lamina and other members of the nucleoskeleton
- OLIGOMERIC
The motor protein _____ is also present in the nucleus, where it is concentrated near the membrane (though it can be found in the nucleoplasm as well.) It associates at the inner nuclear membrane with lamin, actin, and ____.
Motor protein MYOSIN. It associates with lamin, actin, and EMERIN.
Alpha-spectrin is present in the nucleus of non-_____ cells, and confers _____ to the nucleus. It may also be involved in the repair of interstrand DNA cross-links
Present in the nucleus of non-ERYHTROID cells, and confers ELASTICITY to the nucleus.
Emerin is a protein embedded in the inner nuclear membrane and directly binds _____ to anchor the nuclear _____ to the nuclear envelope.
Directly binds LAMINS to anchor the nuclear LAMINA to the nuclear envelope.
LINC complex, found in the nuclear envelope, is responsible for mechanically linking the _____ with the _____.
Mechanically linking the CYTOSKELETON to the NUCLEOSKELETON
Interactions of cells at cell junctions activates signalling pathways that transmit ____ forces to the cytoskeleton –> the cytoskeleton attaches to ____ complexes on the nuclear envelope which transmit the mechanical force to the nucleoskeleton.
Activates signalling pathways that transmit MECHANICAL forces to the cytoskeleton –> the cytoskeleton attaches to LINC complexes at the nuclear envelope which transmit the mechanical force to the nucleoskeleton.
LINC complexes consist of ____ proteins (typically Nesprin) in the outer nuclear membrane and ____ proteins in the inner nuclear membrane. These proteins interact with each other within the perinuclear space.
LINC complexes consist of KASH proteins (typically Nesprin) in the outer nuclear membrane and SUN proteins in the inner nuclear membrane. These proteins interact with each other in the perinuclear space.
SUN proteins help anchor the LINC complex by binding the nuclear _____. They are also important in keeping the inner and outer nuclear membranes together.
LAMINA
Nesprins bind ____ in the cytoplasm. Different Nesprins on LINC complexes bind different cytoskeletal filaments, which confers functional ____ to the linking process.
IFs. Different Nesprins bind different cytoskeletal filaments, which confers functional DIVERSITY to the linking process
