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Biochemistry - Hematology - Oncology

Filamins but Not Janus Kinases Are Substrates of the ASB2a Cullin-Ring E3 Ubiquitin Ligase in Hematopoietic Cells
Published: Monday, August 20, 2012
Author: Isabelle Lamsoul et al.

by Isabelle Lamsoul, Monique Erard, Peter F. M. van der Ven, Pierre G. Lutz

The ASB2a protein is the specificity subunit of an E3 ubiquitin ligase complex involved in hematopoietic differentiation and is proposed to exert its effects by regulating the turnover of specific proteins. Three ASB2a substrates have been described so far: the actin-binding protein filamins, the Mixed Lineage Leukemia protein, and the Janus kinases 2 and 3. To determine the degradation of which substrate drives ASB2a biological effects is crucial for the understanding of ASB2a functions in hematopoiesis. Here, we show that neither endogenous nor exogenously expressed ASB2a induces degradation of JAK proteins in hematopoietic cells. Furthermore, we performed molecular modeling to generate the first structural model of an E3 ubiquitin ligase complex of an ASB protein bound to one of its substrates.