Dual-Specificity Tyrosine Phosphorylation-Regulated Kinase 1A Does Not Require Tyrosine Phosphorylation for Activity in Vitro

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• 作者：Tatyana Adayev ; Mo-Chou Chen-Hwang ; Noriko Murakami ; Eric Lee ; David C. Bolton ; Yu-Wen Hwang
• 刊名：Biochemistry
• 出版年：2007
• 出版时间：June 26, 2007
• 年：2007
• 卷：46
• 期：25
• 页码：7614 - 7624
• 全文大小：421K
• 年卷期：v.46,no.25(June 26, 2007)
• ISSN：1520-4995

文摘

The dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) gene is localizedin human chromosome 21, and its overexpression has been associated with the learning and memorydeficits of Down syndrome. DYRK1A contains a Y³¹⁹XY³²¹ motif shared by all members of the DYRKprotein kinase family. Residue Y321 in the motif is phosphorylated in DYRK1A prepared from Escherichiacoli and from eukaryotic cells. It has been proposed that the YXY motif is an equivalent of the TXYmotif, the activation loop, of mitogen-activated protein kinase and that phosphorylation at the motif isrequired for DYRK activity. In this study, the role of tyrosine phosphorylation in the activity of DYRK1Awas investigated in detail. Wild-type DYRK1A with a reduced level of phosphotyrosine (pY) was preparedby treating E. coli-produced DYRK1A with two different protein tyrosine phosphatases. The resultingpY-depleted DYRK1A could not regain pY during autophosphorylation but was as active as the untreatedcontrol. These findings were further supported by the observation that DYRK1A retained significantenzymatic activity when both tyrosine residues in the YXY motif were replaced with either histidine orglutamine. Together, we conclude that tyrosine phosphorylation and tyrosine residues in the YXY motifare not directly involved in DYRK1A enzymatic activity in vitro.