The need for metabolic mapping in living cells and tissues.
The ultimate activity of an enzyme depends on many regulatory steps from transcription of the gene up to complex formation of the enzyme. Therefore, gene expression (mRNA levels) or protein expression (protein levels) are not reliable parameters to predict the functional activity of an enzyme. Activity measurements in cell homogenates or in frozen or fixed (and thus dead) cell preparations are not appropriate either because post-translational regulation mechanisms that exist in living cells may be lost by homogenization or freezing or chemical fixation of cells. Therefore, metabolic mapping in living cells or, in other words, visualization and quantification using microscopy and image analysis of enzyme reactions in living cells is the approach of choice to understand the functional role of enzymes in vivo as is demonstrated here with a number of examples in recent literature.
Boonacker
Emil
E
Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
Stap
Jan
J
Koehler
Angela
A
Van Noorden
Cornelis J F
CJ
D000818:Animals; D002477:Cells / Q000201:enzymology*; D004798:Enzymes / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D006651:Histocytochemistry / Q000379:methods*; D006801:Humans; D014176:Protein Biosynthesis; D012333:RNA, Messenger; D014158:Transcription, Genetic
D004798:Enzymes; D012333:RNA, Messenger