Expression of Immunoglobin gene

slides on Ig

1. Group Members Maria Idrees Hafiz Jamil Abdul Manan Muhammad Sajawal Bilal Naeem Topic Expression_Of_Immunoglobulin Gene( Ig )

2. Definition :- Protein produce in response to an antigen stimulus with the capacity to bind specifically to the antigen. And after bind antibody eliminate foreign particle or antigen. Antibody is also known as Immunoglobulin gene( Ig ). Antibody

3. It is large Y shaped protein produced mainly by Plasma cells that is used by the Immune System to neutralize pathogens, such as pathogenic bacteria and virus etc. When pathogenic attack Y shaped of antibody bind with antigen. Antibody has specificity, a specific antibody can bind with its specific antigen. Introduction of Antibody

4. Antibodies are Y shaped protein in nature. (glycoprotein) Each tip of the Y of an antibody contain a Paratope that is specific for particular Epitope of an antigen. One end of antibody is Amino terminal(NH 3 ) where an antigen bind. And one end is carboxylic(COOH) Amino terminal end of antibody bind with carboxylic end of antigen. Structure Of Antibody

5. Antibodies are Y shaped glycoprotein and consist of basic structural units:- 2 identical heavy polypeptide chain 2 identical light polypeptide chain Different type of crystalline fragments(F c ) F ab region Hinge region Structure of Antibody (Continue..)

6. Structure of Antibody (continue..)

7. Chains ( heavy and light ) of antibody are connected by Disulphide bond. HEAVY CHAIN 5 type of mammalian Ig heavy chain. IgA, IgD , IgG , IgE , IgM IgA and IgG contain approximately 450 amino acids IgM and IgE contain approximately 550 amino acids Heavy chain have 2 regions Constant region Variable region Explanation

8. LIGHT CHAIN In mammals 2 types of Ig light chain. Lambda Kappa 2 domains constant and variable. Approximate length 211-217 amino acid. Kappa and Lambda are present in mammals. Other types like iota chain are found in vertebrates like sharks and bony fish. Explanation (Continue..)

9. Explanation (continue..)

10. F ab The arms of Y , contain the sites which can bind to antigens are known as Fab ( Fragments antigenic binding regions ) Fab have One constant domain One variable domain Explanation (Continue..)

11. F a b (Continuous..)

12. The base of the Y plays a role in modulating immune cell activity, this region is called Fc(Fragments crystallization) region. Composed of 2 heavy chain. And chains contain 2 or 3 constant domains. F c

13. Processing of primer transcript to remove intervening sequence including non coding introns. And J gene segments not lost during v-(D)-J Rearrangements. Remaining exons are connected by a process called splicing. Final mRNA products is then exported from nucleus and then translated by ribosomes into complete Heavy or Light Chain. Expression

14. Immunoglobulin can exist on either membrane bound or secreted from. Processing can yield different mRNA’s This processing explains the production of secreted or membrane bound forms of a particular immunoglobulin. And the simultaneous expression of IgM and IgD by a single B-Cell. Processing of Heavy Chain

15. Mature B-Cell produce only membrane bound antibody Plasma cell secreted antibody. Expression of membrane bound Ig Controlled by different RNA processing. If the heavy chain transcript is cleaved and polyadenylated at site 2 after the Cu exons, then RNA will encode the membrane form of micro heavy chain. Where membrane bound or secreted Ig formed ?

16. If polyadenylation is instead further downstream at site 4, after the Cs exons. Then RNA splicing will remove intervening Cu exons and produce mRNA encoding the membrane form of the Gemma heavy chain. Continue..

17. The initial pre-mRNA transcript is synthesized. I mportantly, the pre-mRNA transcripts have two poly-A sites within the Cu gene segments. If the M 1 , M 2 exons are spliced out, mRNA for secreted IgM is produced. Expression of membrane bound Ig and secreted Ig

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