9Q5W: Human MDA5 T331I mutant

CryoEM Structure of human MDA5 T331I mutant in complex with dsRNA. Determined by electron microscopy at 3.21 Å resolution. Released 16 Sept 2026.

Method: Electron microscopy
Resolution: 3.21 Å
Organisms: Homo sapiens, synthetic construct
Chains: 4
Atoms: 12,241
Mol. weight: 186.97 kDa
Ligands: ATP
Released: 16 Sept 2026

Explore 9Q5W in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9Q5W contains 62 α-helices and 54 β-strands across 2 chains. Residue ranges use author residue numbering, as in the PDB file, from PDBe. To see them in 3D, choose the Cartoon representation with Secondary structure coloring: helices, sheets and coils get different colors.

Chain C: 30 helices, 28 β-strands

Element	Residues	Length	Sheet
α-helix	310-320	11
β-strand	325-328	4	1
α-helix	335-352	18
β-strand	359-363	5	1
α-helix	366-372	7
α-helix	373-377	5
α-helix	378-380	3
β-strand	387-390	4	1
α-helix	395-397	3
α-helix	400-406	7
β-strand	409-413	5	1
α-helix	414-426	13
β-strand	439-443	5	1
α-helix	445-447	3
α-helix	453-473	21
β-strand	483-488	6	1
α-helix	499-512	14
β-strand	517-519	3	1
α-helix	525-531	7
α-helix	535	1
β-strand	536-539	4	2
β-strand	542	1	3
α-helix	549-565	17
α-helix	572	1
α-helix	576-592	17
α-helix	595-616	22
α-helix	619-640	22
α-helix	671-691	21
α-helix	699-712	14
β-strand	721-725	5	2
α-helix	728-740	13
α-helix	742-747	6
β-strand	751-754	4	2
α-helix	764-767	4
α-helix	768-780	13
β-strand	787-790	4	2
β-strand	794	1	4
β-strand	796	1	4
β-strand	803-807	5	2
α-helix	813-820	8
β-strand	829-833	5	2
β-strand	835	1	3
α-helix	840-862	23
α-helix	866-890	25
α-helix	900-902	3
β-strand	903-907	5	5
β-strand	913-916	4	5
β-strand	921-923	3	6
β-strand	927-929	3	6
α-helix	933-938	6
β-strand	940-941	2	6
β-strand	959-961	3	6
β-strand	967-974	8	6
β-strand	977-982	6	6
β-strand	987-991	5	5
β-strand	996-999	4	5
α-helix	1003-1005	3
β-strand	1012	1	6

Chain I: 32 helices, 26 β-strands

Element	Residues	Length	Sheet
α-helix	310-320	11
β-strand	325-328	4	7
α-helix	335-352	18
β-strand	359-363	5	7
α-helix	366-372	7
α-helix	373-377	5
α-helix	378-380	3
β-strand	387-390	4	7
α-helix	395-397	3
α-helix	400-404	5
β-strand	409-413	5	7
α-helix	414-426	13
β-strand	439-443	5	7
α-helix	445-447	3
α-helix	453-473	21
α-helix	476-482	7
β-strand	483-488	6	7
α-helix	499-512	14
β-strand	517-519	3	7
α-helix	525-531	7
α-helix	533-535	3
β-strand	536-542	7	8
α-helix	549-564	16
α-helix	572	1
α-helix	576-592	17
α-helix	595-616	22
α-helix	620-641	22
α-helix	671-692	22
α-helix	699-713	15
β-strand	721-725	5	8
α-helix	728-740	13
α-helix	742-747	6
β-strand	751-754	4	8
α-helix	764-767	4
α-helix	768-779	12
β-strand	787-790	4	8
β-strand	803-807	5	8
α-helix	813-822	10
β-strand	829-835	7	8
α-helix	840-862	23
α-helix	866-890	25
α-helix	900-902	3
β-strand	903-907	5	9
β-strand	913-916	4	9
β-strand	920-923	4	10
β-strand	927-930	4	10
α-helix	933-938	6
β-strand	940-942	3	11
α-helix	958	1
β-strand	959-961	3	11
β-strand	970	1	11
β-strand	971-974	4	12
β-strand	977-980	4	12
β-strand	981	1	10
α-helix	984-986	3
β-strand	987-991	5	9
β-strand	998	1	9
β-strand	1012	1	10

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Interferon-induced helicase C domain-containing protein 1	C, I	protein	728	Homo sapiens	Q9BYX4 (AlphaFold model)
RNA (29-mer)	B	RNA	29	synthetic construct
RNA (29-mer)	A	RNA	29	synthetic construct

Sequence of entity 1 (C, I), FASTA

>9Q5W_1 Interferon-induced helicase C domain-containing protein 1 (chains C, I)
ARASPEPELQLRPYQMEVAQPALEGKNIIICLPIGSGKTRVAVYIAKDHLDKKKKASEPG
KVIVLVNKVLLVEQLFRKEFQPFLKKWYRVIGLSGDTQLKISFPEVVKSCDIIISTAQIL
ENSLLNLENGEDAGVQLSDFSLIIIDECHHTNKEAVYNNIMRHYLMQKLKNNRLKKENKP
VIPLPQILGLTASPGVGGATKQAKAEEHILKLCANLDAFTIKTVKENLDQLKNQIQEPCK
KFAIADATREDPFKEKLLEIMTRIQTYCQMSPMSDFGTQPYEQWAIQMEKKAAKEGNRKE
RVCAEHLRKYNEALQINDTIRMIDAYTHLETFYNEEKDKKFAVIEDDSDEGGDDEYCDGD
EDEDDLKKPLKLDETDRFLMTLFFENNKMLKRLAENPEYENEKLTKLRNTIMEQYTRTEE
SARGIIFTKTRQSAYALSQWITENEKFAEVGVKAHHLIGAGHSSEFKPMTQNEQKEVISK
FRTGKINLLIATTVAEEGLDIKECNIVIRYGLVTNEIAMVQARGRARADESTYVLVAHSG
SGVIEHETVNDFREKMMYKAIHCVQNMKPEEYAHKILELQMQSIMEKKMKTKRNIAKHYK
NNPSLITFLCKNCSVLACSGEDIHVIEKMHHVNMTPEFKELYIVRENKALQKKCADYQIN
GEIICKCGQAWGTMMVHKGLDLPCLKIRNFVVVFKNNSTKKQYKKWVELPITFPNLDYSE
CCLFSDED

Sequence of entity 2 (B), FASTA

>9Q5W_2 RNA (29-MER) (chains B)
UUCGGUUAGGGGCUAGGACGAUAUUAUUG

Sequence of entity 3 (A), FASTA

>9Q5W_3 RNA (29-MER) (chains A)
CAAUAAUAUCGUCCUAGCCCCUAACCGAA

Ligands and cofactors

ID	Name	Formula	Copies
ATP	Adenosine-5'-triphosphate	C10 H16 N5 O13 P3	2

Primary citation

Unraveling the molecular basis for MDA5 T331I disease-linked mutation. Xu, L., Chung, K., Guo, R. et al. To be published.

Other PDB entries of the same protein (UniProt Q9BYX4 (AlphaFold model), which also has an AlphaFold model), best resolution first:

3GA3 1.45 Å, Crystal structure of the C-terminal domain of human MDA5
3B6E 1.6 Å, Crystal structure of human DECH-box RNA Helicase MDA5 (Melanoma…
9Y4J 2.81 Å, CryoEM Structure of human MDA5 with dsRNA (one protein subunit on dsRNA)
9Y4L 2.96 Å, CryoEM Structure of human MDA5 in complex with dsRNA (two protein subunits on dsRNA)
9LOV 3.07 Å, LGP2:MDA5:dsRNA filament
9Q60 3.12 Å, CryoEM Structure of human MDA5 disease-linked mutant T331I with dsRNA (one protein…
7DNI 3.2 Å, MDA5 CARDs-MAVS CARD polyUb complex
7DNJ 3.3 Å, K63-polyUb MDA5CARDs complex
4GL2 3.56 Å, Structural Basis for dsRNA duplex backbone recognition by MDA5
7JL0 4.3 Å, Cryo-EM structure of MDA5-dsRNA in complex with TRIM65 PSpry domain (Monomer)
7JL2 4.3 Å, Cryo-EM structure of MDA5-dsRNA filament in complex with TRIM65 PSpry domain (Trimer)
2RQB Solution structure of MDA5 CTD

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