University:
Rutgers University Newark
Course:
CHEM 335 | Organic Chemistry
Academic year:

2024
Views:

239

Pages:

43
Author:

Mahitab S.

Stranford Owen Punt Jones Kuby Immunology EIGHTH EDITION Lecture Slides CHAPTER 6 The Organization and Expression of Lymphocyte Receptor Genes Macmilan Laamming 2023 Immunoglobulin Structure Immunoglobulins consist of two heavy chains and two light chains. 5 The V can be corrected t V region Cregion Vregion region T Macmillan Leaming 2023 Fig. 6-1 The Heavy Chain Heavy-chain gene organization includes VH, DH, JH, and CH segments. Mice express approximately 100 VH segments whereas humans express at least 45 functional Vi segments. DH segments are downstream of the VH segments. There are 14 Di segments in mice and 23 in humans. There are 4 JH segments in mice and 6 in humans. Eight CH regions exist and encode different antibody isotypes. Macmillan Leaming 2023 M 45 M 15 Fig. 6-6 Combinatorial Antibody Diversity in Humans Nature of segment Number of heavy- chain segments (estimated) Number of K- chain segments (estimated) Number of A-chain segments (estimated) V 45 41 33 D 23 J 6 5 5 Possible number of combinations 45×23×6=6210 41x5=205 335165 Possible number of heavy- and light-chain immunoglobulin variable region combinations in the human = 6210x (205+165)=2.3 x 10 Macmillan Leaming 2023 Table 6-1 Signal Sequences Direct Recombination Recombination signal s equences (RSSs) flank each gene segment. Each has a conserved nonamer and heptamer sequence. Either a 12- or a 23-bp spacer sequence lies between the nonamer and heptamer. The spacing and arrangement dictate that a 12-bp RSS must pair with a 23-bp RSS for recombination to occur (known as the "12/23 Rule"). Macmillan Leaming 2023 N 00 LV Estain GINA GIONA 12 N 4 1112 Fig 6-8 Production of Light- and Heavy-Chain Variable Regions Germ-ne light dan DNA Reconbinet V] Geam-ine heery chain PINA Ca Can Hramangertent between Vandy Cuntam (12-14 seperasi 14 tutional segments region gene