| immunoglobulin constant region | That region of the immunoglobulin (antibody) molecule that is invariable in its amino acid sequence within any class of immunoglobulins. It confers the biological specificity to the ig and is grossly species specific. It comprises the c-terminus half of the light chains and three quarters or more of the heavy chains, all of the fc fragment, and the c-terminus half of the fab fragment. (12 Dec 1998) |
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| immunoglobulin joining region | Segment of light and heavy chains of mouse and human immunoglobulins where the genes for the variable region upstream join those of the constant region downstream (an important part of the antibody diversity mechanism). In the joining region of the light chain are the genes coding for amino acids 96 to 107. (12 Dec 1998) |
| immunoglobulin switch region | Site on a segment of a B-cell immunoglobulin heavy-chain gene where recombination or rearrangement can occur, expressed as isotype or allotype switching, maturation of immune response, or recombination of DNA molecules. It is found on genes encoding all five immunoglobulin heavy chains. (12 Dec 1998) |
| immunoglobulin variable region | That region of the immunoglobulin (antibody) molecule that varies in its amino acid sequence and composition, confers the antigenic specificity, and is thought to comprise the binding site for the antigen. It is located at the n-terminus of the fab fragment of the immunoglobulin. It includes hypervariable and framework regions, vh family subgroups, and the complementarity-determining region. (12 Dec 1998) |
| inframammary region | The region of the chest inferior to the mammary gland. Synonym: regio inframammaria. (05 Mar 2000) |
| infraorbital region | The region of the face below the orbit and alongside the nose on each side. Synonym: regio infraorbitalis. (05 Mar 2000) |
| infrascapular region | The region of the back lateral to the vertebral region and below the scapula. Synonym: regio infrascapularis. (05 Mar 2000) |
| inguinal region | The topographical area of the inferior abdomen related to the inguinal canal, lateral to the pubic region. Synonym: regio inguinalis, groin, iliac region, inguen. (05 Mar 2000) |
| intergenic region | <molecular biology> DNA sequences located between genes that comprise a large percentage of the human genome with no known function. (09 Oct 1997) |
| intermediate hypothalamic region | The infundibular portion of the hypothalamus, includes the medial tuberal nuclei and portions of the dorsomedial, ventromedial, arcuate (infundibular), posterior and lateral hypothalamic nuclei; located internally in the general area of the infundibulum. (05 Mar 2000) |
| I region | 1. The inducible gene region of the genome of E. Coli involved in the lactose operon. 2. Region of the murine genome coding for products involved in many aspects of the immune response (from Immune Region). most of the products are Class II histocompatibility antigens. (18 Nov 1997) |
| I region associated antigens | Class II major histocompatibility (MHC) antigens. (18 Nov 1997) |
| occipital region of head | The surface region of the head corresponding to the outlines of the occipital bone. Synonym: regio occipitalis capitis. (05 Mar 2000) |
| olfactory region of tunica mucosa of nose | The specialised olfactory receptive area that includes the upper one-third of the nasal septum and the lateral wall above the superior concha; it is lined with olfactory mucosa. Synonym: regio olfactoria tunicae mucosae nasi, olfactory region of tunica mucosa of nose, Schultze's membrane. (05 Mar 2000) |
| operator region | <genetics> DNA sequences which signal the initiation of transcription when derepressed. (12 Dec 1998) |