Dynamin is a minibrain kinase/dual specificity Yak1-related kinase 1A substrate.
The minibrain kinase (Mnbk)/dual specificity Yak 1-related kinase 1A (Dyrk1A) gene is implicated in the mental retardation associated with Down's syndrome. It encodes a proline-directed serine/threonine kinase whose function has yet to be defined. We have used a solid-phase Mnbk/Dyrk1A kinase assay to aid in the search for the cellular Mnbk/Dyrk1A substrates. The assay revealed that rat brain contains two cytosolic proteins, one with a molecular mass of 100 kDa and one with a molecular mass of 140 kDa, that were prominently phosphorylated by Mnbk/Dyrk1A. The 100-kDa protein was purified and identified as dynamin 1. The conclusion was further supported by evidence that a recombinant glutathione S-transferase fusion protein containing dynamin isoform 1aa was phosphorylated by Mnbk/Dyrk1A. In addition to isoform 1aa, Mnbk/Dyrk1A also phosphorylated isoforms 1ab and 2aa but not human MxA protein when analyzed by the solid-phase kinase assay. Upon Mnbk/Dyrk1A phosphorylation, the interaction of dynamin 1 with the Src homology 3 domain of amphiphysin 1 was reduced. However, when Mnbk/Dyrk1A phosphorylation was allowed to proceed more extensively, the phosphorylation enhanced rather than reduced the binding of dynamin 1 to amphiphysin 1. The result suggests that Mnbk/Dyrk1A can play a dual role in regulating the interaction of dynamin 1 with amphiphysin 1. Mnbk/Dyrk1A phosphorylation also reduced the interaction of dynamin with endophilin 1, whereas the same phosphorylation enhanced the binding of dynamin 1 to Grb2. Nevertheless, the dual function of Mnbk/Dyrk1A phosphorylation was not observed for the interaction of dynamin 1 with endophilin 1 or Grb2. The interactions of dynamin with amphiphysin and endophilin are essential for the formation of endocytic complexes; our results suggest that Mnbk/Dyrk1A may function as a regulator controlling the assembly of endocytic apparatus.
Chen-Hwang
Mo-Chou
MC
Molecular Biology Department, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York 10314, USA.
Chen
Huey-Ru
HR
Elzinga
Marshall
M
Hwang
Yu-Wen
YW
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001921:Brain / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D034284:Dynamin I; D034281:Dynamins; D004705:Endocytosis / Q000502:physiology; D051380:GRB2 Adaptor Protein; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D008297:Male; D008970:Molecular Weight; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D051381:Rats; D013379:Substrate Specificity; D018909:src Homology Domains; D000097603:Dyrk Kinases
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D034284:Dynamin I; D034281:Dynamins; D051380:GRB2 Adaptor Protein; D020558:GTP Phosphohydrolases; D009419:Nerve Tissue Proteins; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D011506:Proteins; D000097603:Dyrk Kinases; C495950:Grb2 protein, rat; C075637:amphiphysin