The strain difference and analysis of polymorphic nature of membrane-bound alkaline phosphatase in the midgut epithelium of the silkworm, Bombyx mori

Abstract 1. 1. The enzyme activities, amount of antigen and zymograms of membrane-bound (m-ALP) and soluble (s-ALP) alkaline phosphatases of the midgut were compared in 59 silkworm strains. 2. 2. High correlations were found between the amount of antigen and enzyme activity. 3. 3. Electrophoretograms of ALPs from various strains showed a single s-ALP band and one to tree m-ALP bands. ALP polymorphism was found in m-ALP of several strains but notin the s-ALP. 4. 4. By immunological blotting tests, this polymorphism in m-ALP zymograms correspondend to a 58 kDa polypeptide (single type) or 28, 40 and 58 kDa polypeptides (three bands type), respectively. 5. 5. Polymorphic m_ALPs were separated and characterized. Three eluates from DEAE-Sephacel column chromatography possesed each single active band with different electrophoretic mobilities. 6. 6. Immunological blotting tests revealed that the fastest migrating band comprised two polypeptides (28 and 40 kDa), and the slow and middle bands were monomeric, 58 kDa polypeptides, respectively.