경희대학교 동서의학대학원 의 학 영 양 학 과 김 선 아

and occurs particularly in tissues exhibiting elastic properties, such as skin,
blood vessels and various internal organs. It is a homotrimer composed of
three α1(III) chains and resembles other fibrillar collagens in its structure
and function. Its elastic properties may be due to the disulphide bonds and
the fact that there is no lysyl oxidase-dependent cross-link in the
C-terminal end (Cheung et al. 1983). It is synthesized as procollagen
similarly to type I collagen, but the N-terminal propeptide remains attached
in the mature, fibrillar type III collagen more often than in type I. Mutations
of type III collagen cause the most severe form of Ehlers-Danlos syndrome,
EDS IV, which affect arteries, internal organs, joints and skin, and may
cause sudden death when the large arteries rupture.
Ⅰ-4. Collagen synthesis
The biosynthetic pathway responsible for collagen production is a very
complex one.(Prockop DJ, Kivirikko KI. 1995; Kivirikko KI, Risteli L. 1976)
Each specific collagen type is encoded by a specific gene; the genes for all
of the collagen types are found on a variety of chromosomes. As the
messenger RNA (mRNA) for each collagen type is transcribed from the
gene, or DNA "blueprint," it undergoes many processing steps to produce a
final code for that specific collagen type. This step is called mRNA
processing. Once the final pro-alpha chain mRNA is produced, it attaches to
the site of actual protein synthesis. This step of the synthesis is called
translation. This site of pro-alpha chain mRNA translation is found on the
membrane-bound ribosomes also called the rough endoplasmic reticulum or
rER. Like most other proteins that are destined for function in the
extracellular environment, collagen is also synthesized on the rER.
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