Term
| Stereovilli (inappropriately named stereocilia) |
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Definition
Aid in absorption; Characterized by their length (distinguishing them from microvilli) and their lack of motility (distinguishing them from cilia). They contain actin filaments.
They are found in three regions of the body:
The ductus deferens
The epididymis (see stereocilia (epididymis) for more details)
The inner ear (see stereocilia (inner ear) for more details) |
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Definition
| Tight junctions, or zonula occludens, are the closely associated areas of two cells whose membranes join together forming a virtually impermeable barrier to fluid. |
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Definition
| Cadherins (named for "calcium-dependent adhesion") are a class of type-1 transmembrane proteins. They play important roles in cell adhesion, ensuring that cells within tissues are bound together. |
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Term
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Definition
Adherens junctions (or zonula adherens, intermediate junction, or "belt desmosome"[1]) are protein complexes that occur at cell–cell junctions in epithelial tissues, usually more basal than tight junctions; defined as a cell junction whose cytoplasmic face is linked to the actin cytoskeleton. They can appear as bands encircling the cell (zonula adherens) or as spots of attachment to the extracellular matrix (adhesion plaques).
Composed of cadherins, alpha catenin, beta catenin, gamma catenin, and actin. |
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Term
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Definition
Gamma-catenin, also known as junction plakoglobin, or JUP, is a protein that is common to submembranous plaques of both desmosomes and intermediate junctions.
Mutation of the gene encoding plakoglobin has been implicated as one of the causes of the cardiomyopathy known as arrhythmogenic right ventricular dysplasia (ARVD).
This form of the disorder is autosomal recessive. The phenotype of the Naxos variant of ARVD is unique in that it involves the hair and skin as well as the right ventricle. Affected individuals have wooly, kinky hair; there is also palmar and plantar erythema at birth that progresses to keratosis as the palms and soles of the feet are used in crawling and walking. These findings co-segregate 100% with the development of ARVD by early adolescence. |
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Term
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Definition
Also known as a desmosome; desmosomes help to resist shearing forces and are found in simple and stratified squamous epithelium. The intercellular space is very wide (about 30 nm). Desmosomes are also found in muscle tissue where they bind muscle cells to one another.
Cell adhesion proteins are named desmoglein and desmocollin. |
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Definition
| Infoldings of adjacent cell or plasma membranes. IE thick myosin filaments interdigitate with the thin actin filaments. |
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Definition
Very small stud- or rivet-like structures on the inner basal surface of keratinocytes in the epidermis of skin. They are similar in form to desmosomes when visualized by electron microscopy. While desmosomes link two cells together, hemidesmosomes attach one cell to the extracellular matrix.
Rather than using desmogleins, hemidesmosomes use desmopenetrin cell adhesion proteins. Hemidesmosomes are asymmetrical and are found in epithelial cells connecting the basal face to other cells. |
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Term
| A thioester bond and the two products of its hydrolysis |
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Definition
A thiol (sulfhydryl) and a carboxylic acid.
R-ketone-S-R |
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| Name two features used in naming an enzyme. |
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Definition
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