There are several examples of protein function in our daily life.

1. Mechanism of Protein Function :

In our daily life we see animals like monkeys jumping from one tree to the other or from one building to the others, and gymnastics jumping in an amazing ways. Sometimes humans show remarkable adventurous play.

Children answer some typical questions very quickly. The dogs smell persons and search out the thieves. Out of these, the interesting miracle is how does human brain grasp the diversity of objects, analyses them, restores as memory and works accordingly?

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Obviously, these functions are done by proteins. The speed at which human brain quickly connects the organs is a wonder.

The proteins which carry such information at such a speed are called receptor proteins. These proteins are present on plasma membrane. Presence of is higher than the super-computer.

Over learning in humans all computer is human made, and mind is which a special feature among all creatures is.

How fast mind-stuff (chittavritti) changes? What is the structure of such proteins which bring about such feelings in humans (also in other animals)? How do proteins function? These questions need to be explained.

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2. Protein Deficiency (Malnutrition) – Related Disorders :

The negative aspect of Nature’s Gift to humans is the genetic disorders which arise due to absence of certain key proteins. Some of the examples are discussed below:

(a) Beta-thalasaemia:

It is a severe genetic form of anaemia where patients have abnormally low level of haemoglobin (O2-carrying protein) in erythrocytes (red blood corpuscles).

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The protein globin consists of four different chains or sub-units e.g. beta, delta, gamma-A, gamma-G and epsilon. Lack of beta chain in haemoglobin results in beta-thalasaemia that affects many children. The sufferers survive only by repeated blood transfusion.

(b) Mad Cow Disease and Prions:

In mammals many rare degenerate brain diseases arose due to misfolded proteins. The best known example of these is the mad cow disease, which arose in 1996 in Europe.

Similar diseases in human are Kuru and Creutzfeldt-Jacob (CFJ), and Scrapie in sheep which result in death of the sufferers. S.B. Prusiner who won Nobel Prize in 1997 discovered prion protein (PrP) in brain tissue.

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Disease occurs when normal PrP undergoes conformational changes into PrPSc (where Sc refers scrapie). Structure and function of PrP is not known in detail.

(c) Sickle Cell Anaemia:

Children suffering from sickle cell anaemia have deformed erythrocytes (RBCs). It arises due to mutation in beta chain of haemoglobin protein. The sickle cell haemoglobin (haemoglobin S) molecules precipitate when deoxygenated forming crystalloid aggregates which distort the morphology of RBCs.

The RBCs elongate and form sickle shaped structure. The sickle shaped cells clog small blood vessels and prevents O2 transport to various tissues. In many cases children died due to this disease.

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It is endemic to certain areas of Africa. The 6th amino acid (from NH2– terminal end) of beta chain of haemoglobin is glutamic acid, while haemoglobin S consists valine at the same position. This change in single polypeptide sub-unit has severe effect on phenotype.

(d) Severe Combined Immune-deficiency (SCID):

Babies lacking an enzyme adenosine deaminase suffer from SCID. Such babies cannot survive. Now ex vivo gene therapy is being used applying retrovirus for its treatment.

3. Human Genome Project :

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The Purpose of human genome project was to provide human genome sequence. About 33,000 genes have been sequenced, but the number of protein may be more than 33,000.

Because proteins are further modified through addition of phosphate group (phosphory lation), addition of sugar groups (glycocylation), etc. Different cells, tissues and even sub-cellular organelles have different types of proteins, for example histones in nucleus, haemoglobin in blood, albumin in eggs, prolamine in plants seeds, keratin in hairs, collagen in muscles, etc.

4. Intracellular and Extracellular Proteins :

Proteins synthesised inside the cell may be present within the cell. Such proteins are called intracellular proteins. These proteins are associated with cell organelles and act as enzyme for metabolic activities. On the other hand some proteins are transported outside the cell.

These are called extracellular proteins. These proteins interact with other proteins, DNA, RNA, metal ions, sugars, lipids, etc. and play a vital role in various cell functions. Synthesis of each and every protein is under the control of regulatory units of the gene.

Half life of each protein varies from a few second to hours, months or even years. Human genome sequencing has eased the understanding of sequences of each gene and provided possible remedy of genetic diseases through ‘gene therapy’.

So far over 17,000 proteins have been identified, and function of less number of proteins is known.

Further challenges to biotechnology are (i) to identify proteins expressed by each cell type or tissues, and (ii) to find out the role of each protein that it plays more specifically in understanding the relationship between protein and disease. Such information will lend support to solve the problems of other diseases like prions.