Lm. Corpuz et al., MOLECULAR-CLONING AND TISSUE DISTRIBUTION OF KERATOCAN - BOVINE CORNEAL KERATAN SULFATE PROTEOGLYCAN 37A, The Journal of biological chemistry, 271(16), 1996, pp. 9759-9763
Previous studies showed that the keratan sulfate-containing proteoglyc
ans of bovine corneal stroma contain three unique core proteins design
ated 37A, 37B, and 25 (Funderburgh, J, L,, Funderburgh, M. L., Mann, M
, M,, and Conrad, G, W, (1991) J, Biol, Chem, 266, 14226-14231), Degen
erate oligonucleotides designed from amino acid sequences of the 37A p
rotein were used to screen a cDNA expression library from cultured bov
ine keratocytes, A cDNA clone coding for keratocan, a 37A protein, was
isolated and sequenced. The deduced keratocan amino acid sequence is
unique but related to two other keratan sulfate-containing proteins, l
umican (the 37B core protein) and fibromodulin, These three proteins s
hare approximately 35% amino acid identity and a number of conserved s
tructural features.;Northern hybridization and immunoblotting of tissu
e extracts found keratocan distribution to be more limited than that o
f lumican or fibromodulin, Keratocan is abundant in cornea and sclera
and detected in much lesser amounts in skin, ligament, cartilage, arte
ry, and striated muscles, Only in cornea was keratocan found to contai
n large, sulfated keratan sulfate chains. Keratocan, like lumican, is
a core protein of a major corneal proteoglycan but is present in non-c
orneal tissues primarily as a nonsulfated glycoprotein.