Isozyme profile and tissue-origin of alkaline phosphatases in mouse serum

► Alkaline phosphatase (ALP) was investigated in tissues and serum from wild-type and different ALP knockout mice. ► All mouse tissues, except liver and colon, contained significant ALP activity. ► Mouse serum consists mostly of bone ALP (four bone ALP isoforms) and both intestinal ALP isozymes dIALP and gIALP. ► These results should pave the way for the development of assays measuring bone-specific ALP in mouse serum. ► Since mouse hepatocytes do not express TNALP, we suggest renaming of the mouse gene to Alpb (“b” denotes bone).