Dictionary > Tropocollagen

Tropocollagen

Definition
noun, plural: tropocollagens
A single collagen molecule; a molecular structure that makes up a collagen fiber, and is comprised of three polypeptide chains coiled around each other
Supplement
Tropocollagen is the structural unit of a collagen fiber. It is made up of three polypeptide strands (referred to as alpha peptides) that are twisted together into a super helix or a right-handed triple helix. The amino acids in each chain are arranged in a regular pattern. The typical pattern is Gly-Pro-X or Gly-X-Hyp (the X being any other amino acid residue). An aggregate of tropocollagen is referred to as a fibril.
The synthesis of tropocollagen begins at mRNA transcription of genes that usually have the “COL” prefix. The final mRNA transcript leaves the nucleus and then binds with the ribosomes to begin translation, resulting in the formation of pre-pro-peptide. The pre-pro-peptide moves to the endoplasmic reticulum for post-translational modification. The first modification is the dissolution of the signal peptide on the N-terminal of the pre-pro-peptide, thereby, becoming a propeptide. The propeptide next undergoes lysine and proline hydroxylations through the action of vitamin C (as a cofactor) and enzymes, prolyl hydroxylase and lysyl hydroxylase. This is, then, followed by glycosylation where monosaccharide (glucose or galactose) monomers are added onto the hydroxyl groups of lysines. This leads to the formation of a triple helix structure, now called procollagen, but still with unwound or loose ends. The procollagen is packaged into a transfer vesicle to be transferred to the Golgi apparatus for further post-translational modification. In the Golgi apparatus, oligosaccharides are added to the procollagen and then packaged into a secretory vesicle to be transferred outside the cell. Once outside, the collagen peptidases “trim” the loose ends of the procollagen to become tropocollagen. The enzyme lysyl oxidase aid in the binding of tropocollagen molecules to form an aggregate called collagen fibril.
See also:


You will also like...

primitive arthropods
Arthropods

The arthropods were assumed to be the first taxon of species to possess jointed limbs and exoskeleton, exhibit more adva..

"Opabinia regalis"
The Evolutionary Development of Multicellular Organisms

Multicellular organisms evolved. The first ones were likely in the form of sponges. Multicellularity led to the evolutio..

Pink Lotus plant on a pond
Freshwater Lentic Communities & Animals

This tutorial looks at some of the communities in freshwater lentic habitats. For instance, symbiosis occurs in a commun..

Ploidy
Polyploidy

Humans are diploid creatures. This means that for every chromosome in the body, there is another one to match it. Howeve..

Neural Control Mechanisms
Neural Control Mechanisms

Neurons generate electric signals that they pass along to the other neurons or target tissues. In this tutorial, you wil..

A sperm cell fertilizing an ovum
Human Reproduction and Fertilization

For human species to obviate extinction, reproductive mature adults should be producing viable offspring in order to con..

Related Articles...

No related articles found

See all Related Topics