Contact information

Markku Varjosalo
Tel. +358 2 941 59413
Fax. +358 2 941 59366


Institute of Biotechnology
P.O.Box. 65
00014 University of Helsinki

Street address:
Viikinkaari 1, Biocenter 3

Biocenter Finland


Molecular Systems Biology Research Group and
Proteomics Unit

Group leader

Markku Varjosalo, Ph.D, Docent

University of Helsinki
Institute of Biotechnology
Biocenter 3, 3rd floor
P.O.Box 65 (Viikinkaari 1)
FIN-00014 University of Helsinki Finland


At any given time in any given cell, multiple types of molecular networks are concurrently active. An important feature of these networks is the multiple reversible reactions of protein phosphorylation (catalyzed by protein kinases) and dephosphorylation (catalyzed by protein phosphatases). Protein kinases mediate most of the signal transduction events in cells by phosphorylation of specific substrates - modifying their activity, cellular location, and/or association with other proteins. Protein phosphatases act in opposition to protein kinases thus making themselves also integral to many signal transduction pathways. Protein phosphorylation plays a crucial role in biological functions and controls nearly every cellular process. Therefore, it is easy to understand why changes in the activity of these two important protein groups lead to severe developmental disorders and to diseases like cancer.