ADGF–A EXPRESSION IN LARVAL GUT
EFFECT OF ADGF-A ON Cl.8+ IMAGINAL DISC CELL MORPHOLOGY
EFFECT OF ADGF-A ON IMAGINAL DISC CELL PROLIFERATION
ADENOSINE DEAMINASE ACTIVITY
INACTIVATION OF ADGF ENZYMATIC FUNCTION
CORRELATION OF THE TWO PROTEIN ACTIVITIES in vitro
ADA activity ADGF-A
ADGF-D ADGF-A-Mut
Cell proliferation
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ADENOSINE DEAMINASE IN MAMMALS
• ADA is a 41-kDa protein expressed in all mammalian cells, catalyzes the deamination of adenosine and 2’deoxyinosine to inosine and 2’deoxyinosine. • ADA is a cytosolic enzyme and ectoenzyme. • ADA binds to two cell surface molecules – ADAreceptor and CD26 (dipeptidyldipeptidase IV) – Both play putative roles in signal transduction and have homologs in Drosophila. • Adenosine itself is a signaling molecule characterized by the differential modulation of normal and transformed cell growth, depending upon its extracellular concentration.
HYPOTHETICAL MODEL OF ADGF FUNCTION
ADGFs
• Drosophila has 7 genes encoding ADA-related proteins: ADA, MSI and ADGF-A-E • ADGF-A is expressed in all developmental stages whereas the other members are expressed only in adults and seem to be more male specific • They act as mitogens on imaginal disc cells in vitro • Their mitogenic activity depends on their ADA catalytic activity