Keratan sulfate

Source: Wikipedia, the free encyclopedia.
Not to be confused with Keratin.
Chemical structure of keratan sulfate

Keratan sulfate (KS), also called keratosulfate, is any of several

development[1] and in the glial scar formation following an injury.[2] Keratan sulfates are large, highly hydrated molecules which in joints can act as a cushion to absorb mechanical shock
.

Structure

Like other

osteoadherin, and aggrecan
.

The basic repeating disaccharide unit within keratan sulfate is -3

primary structure of specific KS types are best considered to be composed of three regions:[3]

The monosaccharide mannose is found within the linkage region of keratan sulfate type I (KSI). Disaccharides within the repeating region of KSII may be fucosylated and N-Acetylneuraminic acid caps the end of all keratan sulfate type II (KSII) chains and up to 70% of KSI type chains.[4]

KS classes

The designations KSI and KSII were originally assigned on the basis of the tissue type from which the keratan sulfate was isolated. KSI was isolated from

N-acetylgalactosamine.[8] The tissue based classification of KS no longer exists as KS types have been shown to be non tissue specific.[4] A third type of KS (KSIII) has also been isolated from brain tissue that is O-linked to specific serine or threonine amino acids via mannose.[9]

Corneal KSI

The amount of KS found in the cornea is 10 fold higher than it is in cartilage and 2-4 times higher than it is in other tissues.[10] It is produced by corneal keratocytes[11] and is thought to play a role of a dynamic buffer of corneal hydration. In a rare progressive disorder called macular corneal dystrophy (MCDC), the synthesis of keratan sulfate is either absent (MCDC type I) or abnormal (MCDC type II).[12]

Non-corneal KSI

PRELP are core proteins found in bone and cartilage, that are modified by N-linked KS chains. Osteoadherin and Fibromodulin linked KS chains are shorter than those found in the cornea, typically 8-9 disaccharide units in length.[13] Whereas corneal KSI is composed of a number of domains showing variable degrees of sulphation the longest of which may be 8-32 disaccharide units in length. The non-reducing terminal of Fibromodulin KS is more similar in structure to the non-reducing terminal of a KSII type keratan sulphate rather than to corneal KSI. KS structure is therefore believed to be determined by the tissue specific availability of glycosyltransferases rather than linkage type to the core protein.[4]

KSII

tracheal
KSII where this feature is absent.

See also

References

  1. PMID 9087531
    .
  2. PMID 17185507
    .
  3. PMID 8798563
    .
  4. ^
    PMID 11030741
    .
  5. PMID 13129238
    .
  6. PMID 13592269
    .
  7. PMID 14284693
    .
  8. ^
    PMID 2222415
    .
  9. PMID 2941416
    .
  10. PMID 2957372
    .
  11. PMID 12933807
    .
  12. ^ Macular dystrophy, corneal, 1 - OMIM
  13. PMID 9298700
    .

External links
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