|Title:||Alpha-kinase 1, a new component in apical protein transport||Authors:||Heine, Martin
Cramm-Behrens, Catharina I
Ryazanov, Alexey G
Naim, Hassan Y
|Issue Date:||8-Jul-2005||Journal Volume:||280||Journal Issue:||27||Source:||The Journal of biological chemistry||Abstract:||
A key aspect in the structure of epithelial cells is the maintenance of a polarized organization based on a highly specific sorting machinery for cargo destined for the apical or the basolateral membrane domain at the exit site of the trans-Golgi network. We could recently identify two distinct post-trans-Golgi network vesicle populations that travel along separate routes to the plasma membrane, a lipid raft-dependent and a lipid raft-independent pathway. A new component of raft-carrying apical vesicles is alpha-kinase 1 (ALPK1), which was identified in immunoisolated vesicles carrying raft-associated sucrase-isomaltase (SI). This kinase was absent from vesicles carrying raft-non-associated lactase-phlorizin hydrolase. The expression of ALPK1 increases by the time of epithelial cell differentiation, whereas the intracellular localization of ALPK1 on apical transport vesicles was confirmed by confocal analysis. A phosphorylation assay on isolated SI-carrying vesicles revealed the phosphorylation of a protein band of about 105 kDa, which could be identified as the motor protein myosin I. Finally, a specific reduction of ALPK1-expression by RNA interference results in a significant decrease in the apical delivery of SI. Taken together, our data suggest that the phosphorylation of myosin I by ALPK1 is an essential process in the apical trafficking of raft-associated SI.
|Appears in Collections:||分子與細胞生物學研究所|
|J. Biol. Chem.-2005-Heine-25637-43.pdf||565.46 kB||Adobe PDF||View/Open|
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