9E2E: Actin, alpha cardiac muscle 1

The structure of the junction region of the wild-type murine native cardiac thin filament in Ca2+-free state. Determined by electron microscopy at 4.0 Å resolution. Released 4 Jun 2025.

Method: Electron microscopy
Resolution: 4.0 Å
Organism: Mus musculus
Chains: 16
Atoms: 22,924
Mol. weight: 586.22 kDa
Ligands: MG, ADP
Released: 4 Jun 2025

Explore 9E2E in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9E2E contains 151 α-helices and 120 β-strands across 16 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 A: 24 helices, 19 β-strands

Element	Residues	Length	Sheet
α-helix	6-7	2
β-strand	8-11	4	1
β-strand	16-21	6	1
β-strand	29-32	4	1
β-strand	35-38	4	2
β-strand	53-54	2	2
α-helix	55-58	4
α-helix	62-64	3
β-strand	65-68	4	2
β-strand	71	1	3
β-strand	76	1	3
α-helix	79-88	10
α-helix	89-93	5
α-helix	98-100	3
β-strand	103-107	5	1
α-helix	113-125	13
β-strand	131-136	6	1
α-helix	137-144	8
β-strand	149-155	7	4
β-strand	160-166	7	4
β-strand	169-170	2	4
α-helix	172-174	3
β-strand	176-178	3	4
α-helix	182-192	11
α-helix	193-195	3
α-helix	205-216	12
α-helix	223-232	10
β-strand	238-242	5	5
β-strand	245-250	6	5
α-helix	252-255	4
α-helix	258-261	4
α-helix	264-267	4
α-helix	274-284	11
α-helix	290-295	6
β-strand	297-300	4	4
α-helix	302-305	4
α-helix	309-320	12
β-strand	329-330	2	4
α-helix	338-348	11
α-helix	351-354	4
β-strand	357-358	2	1
α-helix	359-365	7
α-helix	367-371	5

Chain B: 23 helices, 21 β-strands

Element	Residues	Length	Sheet
β-strand	8-9	2	6
β-strand	11	1	7
β-strand	17-19	3	7
β-strand	21	1	6
β-strand	29-31	3	7
β-strand	35-38	4	8
β-strand	53-54	2	8
α-helix	55-59	5
α-helix	62-64	3
β-strand	65-68	4	8
β-strand	71	1	9
β-strand	76	1	9
α-helix	79-87	9
α-helix	88-93	6
α-helix	98-100	3
β-strand	103-107	5	6
α-helix	113-122	10
α-helix	123-127	5
β-strand	131-136	6	6
α-helix	137-144	8
β-strand	150-155	6	10
β-strand	160-166	7	10
β-strand	169-170	2	10
α-helix	172-174	3
β-strand	176-178	3	10
α-helix	182-192	11
α-helix	193-195	3
α-helix	205-216	12
α-helix	223-230	8
β-strand	238-242	5	11
β-strand	245-250	6	11
α-helix	253-256	4
α-helix	258-261	4
α-helix	274-284	11
α-helix	290-295	6
β-strand	297-300	4	10
α-helix	302-304	3
α-helix	309-320	12
β-strand	329-330	2	10
α-helix	338-347	10
α-helix	351-354	4
β-strand	357-358	2	6
α-helix	359-365	7
α-helix	367-369	3

Chain C: 22 helices, 20 β-strands

Element	Residues	Length	Sheet
β-strand	8-11	4	12
β-strand	16-21	6	12
β-strand	29-32	4	12
β-strand	35-38	4	13
β-strand	53-54	2	13
α-helix	55-57	3
β-strand	65-68	4	13
β-strand	71	1	14
β-strand	76	1	14
α-helix	79-88	10
α-helix	89-94	6
α-helix	98-100	3
β-strand	103-107	5	12
α-helix	113-125	13
β-strand	131-136	6	12
α-helix	137-144	8
β-strand	151-155	5	15
β-strand	160-164	5	15
β-strand	165-166	2	16
β-strand	169-170	2	16
α-helix	172-174	3
β-strand	176-178	3	15
α-helix	182-192	11
α-helix	193-195	3
α-helix	203-216	14
α-helix	223-230	8
β-strand	238-243	6	17
β-strand	245-250	6	17
α-helix	253-256	4
α-helix	258-262	5
α-helix	272-273	2
α-helix	274-284	11
α-helix	290-295	6
β-strand	297-300	4	15
α-helix	302-305	4
α-helix	310-320	11
β-strand	329-330	2	15
α-helix	338-347	10
α-helix	351-354	4
β-strand	357-358	2	12
α-helix	359-365	7
α-helix	367-369	3

Chain D: 22 helices, 19 β-strands

Element	Residues	Length	Sheet
β-strand	8-11	4	18
β-strand	16-21	6	18
β-strand	29-32	4	18
β-strand	35-38	4	19
β-strand	53-54	2	19
α-helix	55-59	5
α-helix	62-64	3
β-strand	65-68	4	19
β-strand	71	1	20
β-strand	76	1	20
α-helix	79-87	9
α-helix	88-93	6
α-helix	98-100	3
β-strand	103-107	5	18
α-helix	113-125	13
β-strand	131-136	6	18
α-helix	137-144	8
β-strand	150-155	6	21
β-strand	160-166	7	21
β-strand	169-170	2	21
β-strand	176-178	3	21
α-helix	182-192	11
α-helix	193-195	3
α-helix	205-216	12
α-helix	223-230	8
β-strand	238-242	5	22
β-strand	245-250	6	22
α-helix	253-256	4
α-helix	258-260	3
α-helix	274-284	11
α-helix	290-295	6
β-strand	297-300	4	21
α-helix	302-304	3
α-helix	309-320	12
α-helix	326-327	2
β-strand	329-330	2	21
α-helix	338-347	10
α-helix	351-354	4
β-strand	357-358	2	18
α-helix	359-365	7
α-helix	367-369	3

Chain E: 22 helices, 21 β-strands

Element	Residues	Length	Sheet
β-strand	8-9	2	23
β-strand	11	1	24
β-strand	16-19	4	24
β-strand	21	1	23
β-strand	29-32	4	24
β-strand	35-38	4	25
β-strand	53-54	2	25
α-helix	57-60	4
α-helix	62-64	3
β-strand	65-68	4	25
β-strand	71	1	26
β-strand	76	1	26
α-helix	79-91	13
α-helix	98-100	3
β-strand	103-107	5	23
α-helix	113-122	10
α-helix	123-127	5
β-strand	131-136	6	23
α-helix	137-145	9
β-strand	150-155	6	27
β-strand	160-166	7	27
β-strand	169-170	2	27
β-strand	176-178	3	27
α-helix	182-193	12
α-helix	205-216	12
α-helix	223-230	8
β-strand	238-242	5	28
β-strand	245-250	6	28
α-helix	253-256	4
α-helix	258-261	4
α-helix	272-273	2
α-helix	274-283	10
α-helix	287-289	3
α-helix	290-295	6
β-strand	297-300	4	27
α-helix	302-304	3
α-helix	309-320	12
β-strand	329-330	2	27
α-helix	338-347	10
α-helix	350-352	3
β-strand	357-358	2	23
α-helix	359-365	7
α-helix	366-369	4

Chain F: 23 helices, 20 β-strands

Element	Residues	Length	Sheet
β-strand	8-9	2	29
β-strand	16-19	4	30
β-strand	20-21	2	29
β-strand	29-32	4	30
β-strand	35-38	4	31
β-strand	53-54	2	31
α-helix	55-59	5
α-helix	62-64	3
β-strand	65-68	4	31
β-strand	71	1	32
β-strand	76	1	32
α-helix	79-88	10
α-helix	89-94	6
α-helix	98-100	3
β-strand	103-107	5	29
α-helix	113-125	13
β-strand	131-136	6	29
α-helix	137-144	8
β-strand	150-155	6	33
β-strand	160-166	7	33
β-strand	169-170	2	33
α-helix	172-174	3
β-strand	176-178	3	33
α-helix	182-192	11
α-helix	193-195	3
α-helix	203-216	14
α-helix	223-232	10
β-strand	238-242	5	34
β-strand	245-250	6	34
α-helix	253-256	4
α-helix	258-260	3
α-helix	272-273	2
α-helix	274-283	10
α-helix	290-295	6
β-strand	297-300	4	33
α-helix	302-305	4
α-helix	309-320	12
β-strand	329-330	2	33
α-helix	338-347	10
α-helix	351-354	4
β-strand	357-358	2	29
α-helix	359-365	7
α-helix	366-369	4

Chains G and L: 1 helix, 0 β-strands

Element	Residues	Length	Sheet
α-helix	233-281	49

Chains H and M: 1 helix, 0 β-strands

Element	Residues	Length	Sheet
α-helix	232-281	50

3 more chain groups are not listed. Open the entry in the viewer and use the sequence panel to see them.

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Actin, alpha cardiac muscle 1	A, B, C, D, E, F	protein	377	Mus musculus	P68033 (AlphaFold model)
Tropomyosin alpha-1 chain	G, H, I, J, L, M, N, O	protein	284	Mus musculus	P58771 (AlphaFold model)
Isoform A2 of Troponin T, cardiac muscle	K, P	protein	291	Mus musculus	P50752 (AlphaFold model)

Sequence of entity 1 (A, B, C, D, E, F), FASTA

>9E2E_1 Actin, alpha cardiac muscle 1 (chains A, B, C, D, E, F)
MCDDEETTALVCDNGSGLVKAGFAGDDAPRAVFPSIVGRPRHQGVMVGMGQKDSYVGDEA
QSKRGILTLKYPIEHGIITNWDDMEKIWHHTFYNELRVAPEEHPTLLTEAPLNPKANREK
MTQIMFETFNVPAMYVAIQAVLSLYASGRTTGIVLDSGDGVTHNVPIYEGYALPHAIMRL
DLAGRDLTDYLMKILTERGYSFVTTAEREIVRDIKEKLCYVALDFENEMATAASSSSLEK
SYELPDGQVITIGNERFRCPETLFQPSFIGMESAGIHETTYNSIMKCDIDIRKDLYANNV
LSGGTTMYPGIADRMQKEITALAPSTMKIKIIAPPERKYSVWIGGSILASLSTFQQMWIS
KQEYDEAGPSIVHRKCF

Sequence of entity 2 (G, H, I, J, L, M, N, O), FASTA

>9E2E_2 Tropomyosin alpha-1 chain (chains G, H, I, J, L, M, N, O)
MDAIKKKMQMLKLDKENALDRAEQAEADKKAAEDRSKQLEDELVSLQKKLKGTEDELDKY
SEALKDAQEKLELAEKKATDAEADVASLNRRIQLVEEELDRAQERLATALQKLEEAEKAA
DESERGMKVIESRAQKDEEKMEIQEIQLKEAKHIAEDADRKYEEVARKLVIIESDLERAE
ERAELSEGKCAELEEELKTVTNNLKSLEAQAEKYSQKEDKYEEEIKVLSDKLKEAETRAE
FAERSVTKLEKSIDDLEDELYAQKLKYKAISEELDHALNDMTSI

Sequence of entity 3 (K, P), FASTA

>9E2E_3 Isoform A2 of Troponin T, cardiac muscle (chains K, P)
MSDAEEVVEEYEEEQEEQEEAVEEEEAGGAEPEPEGEAETEEANVEEVGPDEEAKDAEEG
PVEDTKPKPSRLFMPNLVPPKIPDGERVDFDDIHRKRVEKDLNELQTLIEAHFENRKKEE
EELISLKDRIEKRRAERAEQQRIRNEREKERQNRLAEERARREEEENRRKAEDEARKKKA
LSNMMHFGGYIQKQAQTERKSGKRQTEREKKKKILAERRKALAIDHLNEDQLREKAKELW
QSIHNLEAEKFDLQEKFKQQKYEINVLRNRINDNQKVSKTRGKAKVTGRWK

Ligands and cofactors

ID	Name	Formula	Copies
MG	Magnesium ion	Mg	6
ADP	Adenosine-5'-diphosphate	C10 H15 N5 O10 P2	6

Primary citation

The role of the troponin T interactions with actin in regulation of cardiac thin filament revealed by the troponin T pathogenic variant Ile79Asn. Risi, C.M., Landim-Vieira, M., Belknap, B. et al. J Mol Cell Cardiol (2025) 204:55-67. DOI 10.1016/j.yjmcc.2025.05.005 · PubMed

Other PDB entries of the same protein (UniProt P68033 (AlphaFold model), which also has an AlphaFold model), best resolution first:

8ZBN 3.02 Å, Mouse MYH6 R404Q left ventricle ATM complex
8ZIU 3.54 Å, Mouse MYH6 R404Q left ventricle actin and myosin complex
8ZBK 4.28 Å, Mouse left ventricle ATM complex
8ZIP 4.9 Å, Mouse left ventricle actin and myosin complex
9MOW 4.9 Å, Structure of native murine cardiac thin filament variant I79N in troponin T at pCa=5.8…
9MOP 5.0 Å, Structure of native murine cardiac thin filament variant I79N in troponin T at pCa=5.8…
9MOM 5.1 Å, Structure of native murine cardiac thin filament at pCa=5.8 in Ca2+-bound partially…
9MO7 5.2 Å, Structure of native murine cardiac thin filament at pCa=5.8 in Ca2+-bound fully…
9MO8 5.2 Å, Structure of native murine cardiac thin filament at pCa=5.8 in Ca2+-free state (upper…
9MOL 5.2 Å, Structure of native murine cardiac thin filament at pCa=5.8 in Ca2+-free tilted state…
9MON 5.2 Å, Structure of native murine cardiac thin filament at pCa=5.8 in Ca2+-bound fully…
9MOO 5.2 Å, Structure of native murine cardiac thin filament variant I79N in troponin T at pCa=5.8…

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