Biology Reference
In-Depth Information
Table 4.2.
Types of human collagen and the genes that encode them
Collagen type
Constituent chains
Gene symbol
Chromosomal localization
I
1(I)
COL1A1
17q21.3-q22
2(I)
COL1A2
7q22.1
II
1(II)
COL2A1
12q13
III
1(III)
COL3A1
2q31
IV
1(IV)
COL4A1
13q34
2(IV)
COL4A2
13q34
3(IV)
COL4A3
2q36-q37
4(IV)
COL4A4
2q36-q37
5(IV)
COL4A5
Xq22
6(IV)
COL4A6
Xq22
V
1(V)
COL5A1
9q34.2-q34.3
2(V)
COL5A2
2q31
VI
1(VI)
COL6A1
21q22.3
2(VI)
COL6A2
21q22.3
3(VI)
COL6A3
2q37
VII
1(VII)
COL7A1
3p21.3
VIII
1(VIII)
COL8A1
3q12-q13
2(VIII)
COL8A2
1p32.3-p34.2
IX
1(IX)
COL9A1
6q13
2(IX)
COL9A2
1p32.2-p33
3(IX)
COL9A3
20q13.3
X
1(X)
COL10A1
6q21-q22.3
XI
1(XI)
COL11A1
1p21
2(XI)
COL11A2
6p21.3
XII
1(XII)
COL12A1
6q12-q13
XIII
1(XIII)
COL13A1
10q22
XIV
1(XIV)
COL14A1
8q23
XV
1(XV)
COL15A1
9q21-q22
XVI
1(XVI)
COL16A1
1q34
XVII
1(XVII)
COL17A1
10q24.3
XVIII
1(XVIII)
COL18A1
21q22.3
XIX
1(XIX)
COL19A1
6q12-q14
The fibril-associated collagens with interrupted triple helices are distinct from
both the fibrillar and basement membrane collagens. The
COL9A1
,
COL9A2
,
COL12A1,
and
COL19A1
genes are similar in structure indicative of a close evo-
lutionary relationship (Kaleduzzaman
et al
., 1997): all contain some exons of
length 54 bp. The
COL9A1
,
COL12A1,
and
COL19A1
genes are also closely
linked on chromosome 6q12-q14.
The genes encoding the filament-producing collagens,
COL6A1
and
COL6A2
,
possess a similar structure and are closely linked in head-to-tail orientation
(Trikka
et al
., 1997). Although they contain exons of length 45 bp and 54 bp, most
are 63 bp in length. The type VII collagen gene,
COL7A1
, contains 118 exons
some of which are of 45 bp or 54 bp in length but rather more are of 36 bp, the
remainder invariably being multiples of 9 bp (Christiano
et al
., 1994). By contrast
to the extremely fragmented organization of the other collagen genes, the
COL10A1
gene is remarkably compact, containing only three exons.
The evolution of the collagens is thus broadly consistent with a model of gene
duplication and divergence coupled with intragenic exon duplications, deletions
