6kgj
M1Q-hNTAQ1 C28S
Structural highlights
FunctionNTAQ1_HUMAN Mediates the side-chain deamidation of N-terminal glutamine residues to glutamate, an important step in N-end rule pathway of protein degradation. Conversion of the resulting N-terminal glutamine to glutamate renders the protein susceptible to arginylation, polyubiquitination and degradation as specified by the N-end rule. Does not act on substrates with internal or C-terminal glutamine and does not act on non-glutamine residues in any position. Does not deaminate acetylated N-terminal glutamine. With the exception of proline, all tested second-position residues on substrate peptides do not greatly influence the activity. In contrast, a proline at position 2, virtually abolishes deamidation of N-terminal glutamine (By similarity). Publication Abstract from PubMedThe N-degron pathway, formerly the N-end rule pathway, is a protein degradation process that determines the half-life of proteins based on their N-terminal residues. In contrast to the well-established in vivo studies over decades, in vitro studies of this pathway, including biochemical characterization and high-resolution structures, are relatively limited. In this study, we have developed a unique fusion technique using microtubule-associated protein 1A/1B light chain 3B, a key marker protein of autophagy, to tag the N-terminus of the proteins involved in the N-degron pathway, which enables high yield of homogeneous target proteins with variable N-terminal residues for diverse biochemical studies including enzymatic and binding assays and substrate identification. Intriguingly, crystallization showed a markedly enhanced probability, even for the N-degron complexes. To validate our results, we determined the structures of select proteins in the N-degron pathway and compared them to the PDB-deposited proteins. Furthermore, several biochemical applications of this technique were introduced. Therefore, this technique can be used as a general tool for the in vitro study of the N-degron pathway. Use of the LC3B-fusion technique for biochemical and structural studies of proteins involved in the N-degron pathway.,Kim L, Kwon DH, Heo J, Park MR, Song HK J Biol Chem. 2020 Jan 9. pii: RA119.010912. doi: 10.1074/jbc.RA119.010912. PMID:31919097[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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