The ability of an individual to produce an extremely large number of immunoglobulin molecules (~3 × 10¹¹) with a relatively small number of genes has evolved through special genetic mechanisms. This occurs because the immunoglobulin genes undergo somatic recombination, which generates an enormous diversity of antibody specificities.

Each immunoglobulin chain consists of a variable (V) and a constant (C) region. For each type of immunoglobulin chain, that is, kappa light chain (κ), lambda light chain (λ), and the five heavy chains (γH, μH, αH, δH, and εH), there is a separate pool of gene segments located on different chromosomes. In humans the multigene families are found on the following chromosomes: λ, chromosome 22; κ, chromosome 2; and the heavy chain family, chromosome 14. Each of the three gene loci contains a set of different V gene segments that are separated from the C gene segments. During B-cell differentiation, the DNA is rearranged to bring the identified gene segments adjacent to each other in the genome.

In summary, the gene rearrangement process is complex and involves a number of steps. The variable region of each L chain is encoded by two gene segments: V and J. The variable region of each H chain is encoded by three gene segments: V, D, and J. The segments are united into one functional V-variable gene by DNA rearrangement. Each assembled V-variable gene is then transcribed with the appropriate C-constant gene to produce a messenger RNA (mRNA) that encodes for the complete peptide chain. L and H chains are synthesized separately on polysomes and then assembled in the cytoplasm to form H2 L2 chain units. The carbohydrate portion of the Ig molecule is then added during passage through the membrane components of the cell (eg, Golgi apparatus), and the immunoglobulin molecule is released from the cell.

T his gene rearrangement mechanism generates an enormous variety of immunoglobulin molecules. Antibody diversity depends on (1) multiple V, D, and J gene segments; (2) combinatorial association, that is, the association of any V gene segment with any D or J segment; (3) the random combining of different L and H chains; (4) somatic hyper mutation; and (5) junctional diversity produced by imprecise joining during rearrangement.

اخر الاخبار

اخبار العتبة العباسية المقدسة

العتبة العباسية المقدسة تحيي ذكرى شهادة الإمام السجاد (عليه السلام)

العتبة العباسية المقدسة تنشر لافتات خاصة بذكرى شهادة الإمام زين العابدين (عليه السلام)

قسم شؤون المعارف ينظّم دورة مختصة بتحقيق المخطوطات لطلبة الحوزة العلمية النجف الأشرف

قسم التطوير ينظم دورات وورشا تدريبية لطلبة أكاديمية التطوير الإداري

المزيد

الآخبار الصحية

دراسة علمية تكشف مفاجأة حول الأسباب الحقيقية للسمنة

دراسة: الأطباء يتجاهلون "سببا شائعا" لارتفاع ضغط الدم

نظامك الغذائي غني بالبروتين؟.. احذر هذه الآثار الجانبية

لا تتجاهلها.. أعراض تنذرك بأنك مهدد بالإصابة بالسكري

المزيد

الآخبار التكنلوجية

ISOFIX: معيار الأمان الذهبي لمقاعد الأطفال في السيارات

هل المحرك الأكبر دائمًا الأفضل للسيارة؟

اختبارات ناجحة لمحرك "VK-800" الروسي وتطويره لطائرة بايكال الخفيفة

رئيس إنفيديا: الذكاء الاصطناعي الصيني "محفز للتقدم العالمي"

المزيد

مواضيع ذات صلة

Antibody Responses

Immunoglobulin Classes

Immunofluorescence

Chemiluminescence

Enzyme Immunoassay

Capillary Electrophoresis

Antibody Structure and Function

B Cell Receptor for Antigen

Antigen Processing and Presentation

Methods of Enhancing Agglutination

Mechanisms of Agglutination

The Major Histocompatibility Complex