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Ig superfamily, immunology and then the Genesis concert

Posted by iskanbasal on July 16, 2007

Saturday evening there were the Genesis here in Rome, the rock band of Phil Collins, Mike Rutherford, Tony Banks . Great music . It is hot these days here in Rome and in the last saturday in the afternoon I decided to go outdoors to read in a small park called “Villa Celimontana”. This is situated opposite to the military hospital “Il Celio”. all very near to the Colosseum, the ancient Roman theatre, the important destination of the whole turism in Rome.

I read few pages on Abul K. Abbas and andrew H. Lichtman cellular and molecular immunology, the Italian translation. This textbook of immunology which I like as it makes immunology easy to understand and give the important basics for those conditions which have immunologic pathogenesis.

When I read a subject, a chapter, with the purpose of reviewing I do it with a different leaning. I understand things better comprehend them and hold them better. I better enjoy the basic science behind the issues I read. It is different than the first time I read the issues to take tests.

One of the things I enjoyed reading saturday evening was chapter 3: “Antibodies and Antigens”, the precise structure of the antibodies, the domain structure. The domains are segments of the antibody molecule which have a very particular tertiary structure and it is globular in its shape. there are two globular domains in the light chain of the antibody one makes the Variable domain(V) and the the other makes the constant (C) domain; while there are more domains in the structure of the heavy chain of an antibody.

Not only antibodies or immunoglobulins have this kind of domain structure, there are also many other molecules that have this characteristic.

What domains are ?

Domains also called Ig homology units, which are regions of 70 to 110 amino acid residues homologous to either Ig variable (V) or Ig constant (C) domains. The Ig domain contains conserved residues that permit the polypeptide to assume a globular tertiary structure called an antibody (or Ig) fold, composed of a sandwich arrangement of two β-sheets, each made up of three to five antiparallel β-strands of five to ten amino acid residues. This sandwich-like structure is stabilized by hydrophobic amino acid residues on the β-strands pointing inward, which alternate with hydrophilic residues pointing out. Because the inward-pointing residues are essential for the stability of the tertiary structure, they are the major contributors to the regions that are conserved between Ig superfamily members. In addition, there are usually conserved cysteine residues that contribute to the formation of an intrachain disulfide-bonded loop of 55 to 75 aminoacids. Ig domains are classified as V-like or C-like on the basis of closest homology to either Ig V or Ig C domains.

The proteins which have this type of characteristic structure are making a whole family called the Ig Superfamily: “A superfamily is broadly defined as a group of proteins that share a certain degree of sequence homology, usually at least 15%. The conserved sequences shared by superfamily members often contribute to the formation of compact tertiary structures referred to as domains, and most often the entire sequence of a domain characteristic of a particular superfamily is encoded by a single exon”.

All members of the Ig superfamily are cell surface and soluble molecules that share similar functions, Recognition: think the antibodies, Adhesion and Binding functions. Some of these members are the antibodies themselves, the TCR: the T-cell receptor, has domains in its two chains alpha and beta chains, MHC class I and class II, CD2, CD3, CD4, CD8, CD28, B7, ICAM-1, VCAM-1, PDGFR, and many others:”Most identified members of the Ig superfamily are integral plasma membrane proteins with Ig domains in the extracellular portions, transmembrane domains composed of hydrophobic aminoacids, and widely divergent cytoplasmic tails, usually with no intrinsic enzymatic activity”.

After reading this subject I closed the book and started leaving the park. When I reached the road which takes to Circo Massimo I saw thousands of persons directed there. Circo Massimo is an open Roman ruin that cover a very large area and represent an open space where many times musical concerts take place. I understood there were the Genesis. I joined the crowds and finished there: In Circo Massimo.

This Circo Massimo is considered the greatest in the old ages, it is 600m long and 140m large. At 9:30 p.m the genesis begun their concert and Phil Collins accompanied by his colleagues made wonderful music until late in the night. I left there when phil Collins was singing ” effetto domino”: he first described it: Dominio is domain but it is completely different than the domain structure about which I was reading early in the afternoon.

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