Proteins constitute a large part of the cells and are present widely in all tissues. They perform a variety of specialized and essential functions in the living cells.
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Proteins are primarily responsible for the structure and strength of the body. Collagen is a fibrous protein found in the connective tissues. Elastin is found in the bone matrix and vascular systems. Keratin is present in epidermal tissues. Proteins form important structural components of the plasma membrane of the cell.
Microtubules of flagella are made up of the protein called tubulins.
Muscle fibers consist of thin filaments of actin, tropomyosin and troponin.
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Haemoglobin present in blood is a conjugated protein which facilitates the transport of oxygen. Myoglobin present is muscles stores oxygen.
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Some antibiotics are peptides (Examples: Penicillin G, Gramicidin S)
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Albumin is the most abundant plasma protein and is synthesized in the liver. It helps maintain the osmotic pressure of plasma and is involved in transport of variety of substances.
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Nucleoproteins are conjugated proteins. (Examples: Histones, protamines )
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Enzymes are specialized proteins produced in the body which act as biocatalyst by catalyzing specific reactions.
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Several hormones are peptides and proteins which play an important role in regulation of metabolic reactions. Some of them are Insulin, Renin, Calcitonin, Oxytocin, Gastrin, Glucagon etc.
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Storage protein which include egg albumin
