Cytokeratins, Moll numbers

Basic cytokeratins, type II
Moll number	molecular weight (kD)3
1	67
2	65
3	64
4	59
5	58
6	56
7	54
8	52

In addition to the 20 "soft" keratins listed here, there are ten "hard" keratins, restricted to hair and nail epithelia2,3.

Acidic cytokeratins, type I
Moll number	molecular weight (kD)3
9	64
10	56.5
11	56
12	55
13	51
14	50
15	50
16	48
17	46
18	45
19	40
20	46

The original classifications of cytokeratins was based on 2D gel electrophoresis. However, a number of Cytokeratin isotype-specific monoclonal antibodies are now available, reactive on paraffin-embedded tissues. Because of homology between the cytokeratins, monoclonal antibodies need to be screened carefully for cross-reactivity. Epitope may be masked in some circumstances: there may be reactivity on immunoblotting but not in tissue sections. Apparent differentiation-associated changes in reactivity may be due to either changes in cytokeratin expression or conformational changes1. Cytokeratin 20 shows a marked divergence from the conservation seen in the other keratins3.

References

Dako catalogue 2000/2001

Novocastra catalogue 2001

Diagnostic Immunohistochemistry edited by Professor D. J. Dabbs, page 60.

1Southgate, J, Harnden, P., Trejdosiewicz, L. K. Cytokeratin expression patterns in normal and malignant urothelium: a review of the biological and diagnostic implications. Histol Histopathol 1999;14:657-664.

2Remotti, F., Fetsch, J. F., Miettinen, M. Keratin 1 expression in endothelia and mesenchymal tumors: an immunohistochemical analysis of normal and neoplastic tissues. Hum Pathol 2001;32:873-879.

3Chu, P. G. and L. M. Weiss (2002). "Keratin expression in human tissues and neoplasms." Histopathology 40(5): 403-39.

This page last revised 5.11.2001.