| actin | <cell biology> A filamentous proteins (42 kD) involved in muscle contraction in both smooth and striated muscle and also serves as an important structural molecule for the cytoskeleton of many eukaryotic cells. It is the main constituent of the thin filaments of muscle fibres. The filaments (known also as filamentous or f-actin) can be dissociated into their globular subunits; each subunit is composed of a single polypeptide 375 amino acids long. This is known as globular or g-actin. In conjunction with myosin, actin is responsible for the contraction and relaxation of muscle. See: myosin. (25 Jun 1999) |
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| actin filament | One of the contractile elements in muscular fibres and other cells; in skeletal muscle, the actin filament's are about 5 nm wide and 100 um long, and attach to the transverse Z filament's. (05 Mar 2000) |
| actin kinase | <enzyme> Phosphorylates actin at threonine-201 and probably at thr(202) and/or thr(203) Registry number: EC 2.7.1.- Synonym: actin-fragmin kinase (26 Jun 1999) |
| actin N-acetylaminopeptidase | <enzyme> Catalyses the amino-terminal processing of actin by removal of acetylmethionine from the amino terminus for class I actins or the removal of the second residue as an n-acetylamino acid for class II actins Registry number: EC 3.4.11.- (26 Jun 1999) |
| actinal | <zoology> Pertaining to the part of a radiate animal which contains the mouth. Origin: Gr, ray. Source: Websters Dictionary (01 Mar 1998) |
| actinaria | <zoology> A large division of Anthozoa, including those which have simple tentacles and do not form stony corals. Sometimes, in a wider sense, applied to all the Anthozoa, expert the Alcyonaria, whether forming corals or not. Origin: NL, from Gr, ray. Source: Websters Dictionary (01 Mar 1998) |
| acting out | Expressing unconscious emotional conflicts or feelings, often of hostility or love, through overt behaviour. (12 Dec 1998) |
| actinia | <zoology> An animal of the class Anthozoa, and family Actinidae. From a resemblance to flowers in form and colour, they are often called animal flowers and sea anemones. [See Polyp. A genus in the family Actinidae. Source: Websters Dictionary (01 Mar 1998) |
| actinic | Relating to the chemically active rays of the electromagnetic spectrum. Origin: G. Aktis (aktin-), a ray (05 Mar 2000) |
| actinic cheilitis | Mucosal atrophy with drying, crusting, and fissuring of the vermillion border of the lower lip in older individuals, resulting from chronic exposure to sunlight; dysplastic (premalignant) changes are noted microscopically, analogous to solar keratosis. Synonym: actinic cheilitis. (05 Mar 2000) |
| actinic conjunctivitis | Acute keratoconjunctivitis resulting from exposure to intense ultraviolet irradiation. Synonym: actinic conjunctivitis, arc-flash conjunctivitis, flash keratoconjunctivitis, ophthalmia nivalis, snow conjunctivitis, welder's conjunctivitis. (05 Mar 2000) |
| actinic dermatitis | Dermatitis caused or elicited by exposure to sunlight; may be phototoxic or photoallergic, and can result from topical application, ingestion, inhalation, or injection of mediating phototoxic or photoallergic material. See: photosensitization. Synonym: actinic dermatitis, actinodermatitis. Origin: photo-+ G. Derma, skin, + -itis, inflammation (05 Mar 2000) |
| actinic granuloma | An annular eruption on sun-exposed skin which microscopically shows phagocytosis of dermal elastic fibres by giant cells and histiocytes. Synonym: Miescher's granuloma. (05 Mar 2000) |
| actinic keratitis | A reaction of the cornea to ultraviolet light. (05 Mar 2000) |
| actinic keratosis | <dermatology> A skin lesion that is abnormally sensitive to the effects of ultraviolet light (sunlight). Thought to be a precancerous skin lesion that is more common in the fair-skinned or elderly individual. Approximately 20% of these skin lesions will develop into squamous cell carcinoma. Prevention includes the use of sun screen agents and the avoidance of drugs (for example tetracyclines) known to cause photosensitivity reactions. Usually a discreet slightly raised, red or pink lesion located on a sun exposed surface. Texture may appear as rough, gritty or scaly. Growths may be biopsied to look for cancer or removed via cryotherapy or electrical cautery. Some topical agents may be used to promote peeling. (27 Sep 1997) |
| G actin | <protein> A short polypeptide chain of 375 amino acids which is the monomeric unit of the protein actin (one of the two proteins involved in muscle contraction). Many units of G actin join together in a polymer to make an actin filament. (09 Oct 1997) |
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| globular actin | <protein> A short polypeptide chain of 375 amino acids which is the monomeric unit of the protein actin (one of the two proteins involved in muscle contraction). Many units of G actin join together in a polymer to make an actin filament. (09 Oct 1997) |
| Nuclear actin binding protein | <molecular biology> Nuclear protein, dimer of 34 kD subunits. Binds actin with Kd of around 25M. (18 Nov 1997) |
| F actin | <cell biology> Plasmid that confers the ability to conjugate (i.e. Fertility) on bacterial cells and carries the tra genes. It was first described in E. Coli. (18 Nov 1997) |