7KO4: Actin, alpha skeletal muscle

Structure of cardiac native thin filament at pCa=5.8 having upper and lower troponins in Ca2+ free state. Determined by electron microscopy at 8.0 Å resolution. Released 24 Mar 2021.

Method: Electron microscopy
Resolution: 8.0 Å
Organism: Sus scrofa
Chains: 29
Atoms: 61,463
Mol. weight: 1013.22 kDa
Released: 24 Mar 2021

Explore 7KO4 in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

7KO4 contains 431 α-helices and 344 β-strands across 29 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: 3 helices, 0 β-strands

Element	Residues	Length
α-helix	88-148	61
α-helix	200-215	16
α-helix	226-270	45

Chain A: 26 helices, 22 β-strands

Element	Residues	Length	Sheet
α-helix	6-7	2
β-strand	8-12	5	1
β-strand	16-21	6	1
β-strand	22	1	2
β-strand	24	1	2
β-strand	29-32	4	1
β-strand	35-38	4	3
β-strand	53-54	2	3
α-helix	56-60	5
α-helix	62-64	3
β-strand	65-68	4	3
β-strand	71-72	2	4
β-strand	75-76	2	4
α-helix	79-86	8
α-helix	87-93	7
α-helix	98-100	3
β-strand	103-107	5	1
α-helix	113-125	13
β-strand	131-136	6	1
α-helix	137-145	9
β-strand	150-153	4	5
β-strand	160	1	6
β-strand	163-166	4	5
β-strand	169-170	2	5
α-helix	172-174	3
β-strand	178	1	6
α-helix	182-195	14
α-helix	203-216	14
α-helix	223-230	8
α-helix	234-236	3
β-strand	238-241	4	7
β-strand	247-250	4	7
α-helix	253-256	4
α-helix	258-261	4
α-helix	264-267	4
α-helix	274-283	10
α-helix	290-294	5
β-strand	297-299	3	5
α-helix	309-320	12
α-helix	322	1
β-strand	329-330	2	5
α-helix	338-347	10
α-helix	350-352	3
α-helix	356	1
β-strand	357-358	2	1
α-helix	361-365	5
α-helix	367-369	3
α-helix	370-373	4

Chain b: 6 helices, 0 β-strands

Element	Residues	Length
α-helix	43-79	37
α-helix	81-83	3
α-helix	90-140	51
α-helix	141-143	3
α-helix	150-153	4
α-helix	157-183	27

Chain B: 25 helices, 22 β-strands

Element	Residues	Length	Sheet
β-strand	8-12	5	8
β-strand	16-21	6	8
β-strand	22	1	9
β-strand	24	1	9
β-strand	29-32	4	8
β-strand	35-38	4	10
β-strand	53-54	2	10
α-helix	56-60	5
α-helix	62-64	3
β-strand	65-68	4	10
β-strand	71-72	2	11
β-strand	75-76	2	11
α-helix	79-87	9
α-helix	88-94	7
α-helix	98-100	3
β-strand	103-107	5	8
α-helix	113-125	13
β-strand	131-136	6	8
α-helix	137-143	7
β-strand	150-155	6	12
β-strand	160	1	12
β-strand	163-166	4	12
β-strand	169-170	2	12
α-helix	172-174	3
β-strand	178	1	12
α-helix	182-195	14
α-helix	203-216	14
α-helix	223-230	8
α-helix	234-236	3
β-strand	238-241	4	13
β-strand	247-250	4	13
α-helix	253-259	7
α-helix	264-267	4
α-helix	274-283	10
α-helix	287-294	8
β-strand	297-301	5	12
α-helix	309-318	10
α-helix	322	1
α-helix	326-327	2
β-strand	329-330	2	12
α-helix	338-348	11
α-helix	350-352	3
α-helix	356	1
β-strand	357-358	2	8
α-helix	361-365	5
α-helix	367-369	3
α-helix	370-373	4

Chain c: 11 helices, 4 β-strands

Element	Residues	Length	Sheet
α-helix	5-10	6
α-helix	14-24	11
α-helix	25-27	3
β-strand	37	1	20
α-helix	38-40	3
α-helix	41-47	7
α-helix	54-62	9
β-strand	71	1	20
α-helix	74-81	8
α-helix	94-104	11
β-strand	111-112	2	21
α-helix	114-122	9
α-helix	130-140	11
β-strand	148-149	2	21
α-helix	150-156	7

Chain C: 24 helices, 21 β-strands

Element	Residues	Length	Sheet
β-strand	8-12	5	14
β-strand	16-21	6	14
β-strand	29-32	4	14
β-strand	35-38	4	15
β-strand	42	1	5
β-strand	53-54	2	15
α-helix	56-60	5
α-helix	62-64	3
β-strand	65-68	4	15
β-strand	71-72	2	16
β-strand	75-76	2	16
α-helix	79-87	9
α-helix	88-93	6
α-helix	98-100	3
β-strand	103-107	5	14
α-helix	113-125	13
β-strand	131-136	6	14
α-helix	137-145	9
β-strand	150-154	5	17
β-strand	160	1	18
β-strand	163-166	4	17
β-strand	169-170	2	17
α-helix	172-174	3
β-strand	178	1	18
α-helix	182-195	14
α-helix	203-216	14
α-helix	223-230	8
α-helix	234-236	3
β-strand	238-241	4	19
β-strand	247-250	4	19
α-helix	253-259	7
α-helix	264-267	4
α-helix	274-283	10
α-helix	287-294	8
β-strand	297-300	4	17
α-helix	309-318	10
α-helix	322	1
β-strand	329-330	2	17
α-helix	338-347	10
α-helix	350-352	3
α-helix	356	1
β-strand	357-358	2	14
α-helix	361-365	5
α-helix	367-369	3
α-helix	370-373	4

Chain D: 26 helices, 21 β-strands

Element	Residues	Length	Sheet
α-helix	6-7	2
β-strand	8-12	5	22
β-strand	16-21	6	22
β-strand	29-32	4	22
β-strand	35-38	4	23
β-strand	42	1	12
β-strand	53-54	2	23
α-helix	56-60	5
α-helix	62-64	3
β-strand	65-68	4	23
β-strand	71-72	2	24
β-strand	75-76	2	24
α-helix	79-87	9
α-helix	88-93	6
α-helix	98-100	3
β-strand	103-107	5	22
α-helix	114-125	12
β-strand	131-136	6	22
α-helix	137-145	9
β-strand	150-153	4	25
β-strand	160	1	26
β-strand	163-166	4	25
β-strand	169-170	2	25
α-helix	172-174	3
β-strand	178	1	26
α-helix	182-195	14
α-helix	203-216	14
α-helix	223-230	8
α-helix	234-236	3
β-strand	238-241	4	27
β-strand	247-250	4	27
α-helix	253-256	4
α-helix	258-261	4
α-helix	264-267	4
α-helix	274-283	10
α-helix	287-294	8
β-strand	297-299	3	25
α-helix	309-318	10
α-helix	322	1
β-strand	329-330	2	25
α-helix	338-348	11
α-helix	350-355	6
α-helix	356	1
β-strand	357-358	2	22
α-helix	361-365	5
α-helix	367-369	3
α-helix	370-373	4

Chain E: 26 helices, 21 β-strands

Element	Residues	Length	Sheet
α-helix	6-7	2
β-strand	8-12	5	28
β-strand	16-21	6	28
β-strand	29-32	4	28
β-strand	35-38	4	29
β-strand	42	1	17
β-strand	53-54	2	29
α-helix	56-60	5
α-helix	62-64	3
β-strand	65-68	4	29
β-strand	71-72	2	30
β-strand	75-76	2	30
α-helix	79-86	8
α-helix	87-93	7
α-helix	98-100	3
β-strand	103-107	5	28
α-helix	113-125	13
β-strand	131-136	6	28
α-helix	137-145	9
β-strand	150-153	4	31
β-strand	160	1	32
β-strand	163-166	4	31
β-strand	169-170	2	31
α-helix	172-174	3
β-strand	178	1	32
α-helix	182-195	14
α-helix	203-216	14
α-helix	223-230	8
α-helix	234-236	3
β-strand	238-241	4	33
β-strand	247-250	4	33
α-helix	253-256	4
α-helix	258-261	4
α-helix	264-267	4
α-helix	274-283	10
α-helix	287-293	7
β-strand	297-299	3	31
α-helix	309-320	12
α-helix	322	1
β-strand	329-330	2	31
α-helix	338-347	10
α-helix	350-354	5
α-helix	356	1
β-strand	357-358	2	28
α-helix	361-365	5
α-helix	367-369	3
α-helix	370-373	4

17 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 skeletal muscle	A, B, C, D, E, F, G, H, I, J, K, L, M, N, O	protein	375	Sus scrofa	P68137 (AlphaFold model)
Tropomyosin alpha-1 chain	P, Q, R, S, W, X, Y, Z	protein	286	Sus scrofa	A0AAQ4NSK5 (AlphaFold model)
Isoform 4 of Troponin T, cardiac muscle	T, a	protein	186	Sus scrofa	I3LS66 (AlphaFold model)
Troponin I, cardiac muscle	U, b	protein	170	Sus scrofa	A0A4X1V520 (AlphaFold model)
Troponin C	V, c	protein	160	Sus scrofa	P63317

Sequence of entity 1 (A, B, C, D, E, F, G, H, I, J, K, L, M, N, O), FASTA

>7KO4_1 Actin, alpha skeletal muscle (chains A, B, C, D, E, F, G, H, I, J, K, L, M, N, O)
DEDETTALVCDNGSGLVKAGFAGDDAPRAVFPSIVGRPRHQGVMVGMGQKDSYVGDEAQS
KRGILTLKYPIEHGIITNWDDMEKIWHHTFYNELRVAPEEHPTLLTEAPLNPKANREKMT
QIMFETFNVPAMYVAIQAVLSLYASGRTTGIVLDSGDGVTHNVPIYEGYALPHAIMRLDL
AGRDLTDYLMKILTERGYSFVTTAEREIVRDIKEKLCYVALDFENEMATAASSSSLEKSY
ELPDGQVITIGNERFRCPETLFQPSFIGMESAGIHETTYNSIMKCDIDIRKDLYANNVMS
GGTTMYPGIADRMQKEITALAPSTMKIKIIAPPERKYSVWIGGSILASLSTFQQMWITKQ
EYDEAGPSIVHRKCF

Sequence of entity 2 (P, Q, R, S, W, X, Y, Z), FASTA

>7KO4_2 Tropomyosin alpha-1 chain (chains P, Q, R, S, W, X, Y, Z)
ASMDAIKKKMQMLKLDKENALDRAEQAEADKKAAEDRSKQLEDELVSLQKKLKGTEDELD
KYSEALKDAQEKLELAEKKATDAEADVASLNRRIQLVEEELDRAQERLATALQKLEEAEK
AADESERGMKVIESRAQKDEEKMEIQEIQLKEAKHIAEDADRKYEEVARKLVIIESDLER
AEERAELSEGKCAELEEELKTVTNNLKSLEAQAEKYSQKEDRYEEEIKVLSDKLKEAETR
AEFAERSVTKLEKSIDDLEDELYAQKLKYKAISEELDHALNDMTSI

Sequence of entity 3 (T, a), FASTA

>7KO4_3 Isoform 4 of Troponin T, cardiac muscle (chains T, a)
FDDIHRKRMEKDLNELQALIEAHFENRKKEEEELVSLKDRIERRRAERAEQQRIRNEREK
ERQNRLAEERARREEEENRRKAEDEARKKKALSNMMHFGGYIQKQAQTERKSGKRQTERE
KKKKILAERRKVLAIDHLNEDQLREKAKELWQSIYNLEAEKFDLQEKFKQQKYEINVLRN
RINDNQ

Sequence of entity 4 (U, b), FASTA

>7KO4_4 Troponin I, cardiac muscle (chains U, b)
ISASRKLQLKTLLLQIAKQELEREAEERRGEKGRALSTRCQPLELAGLGFAELQDLCRQL
HARVDKVDEERYDIEAKVTKNITEIADLTQKIFDLRGKFKRPTLRRVRISADAMMQALLG
ARAKESLDLRAHLKQVKKEDTEKENREVGDWRKNIDALSGMEGRKKKFES

Sequence of entity 5 (V, c), FASTA

>7KO4_5 Troponin C (chains V, c)
DDIYKAAVEQLTEEQKNEFKAAFDIFVLGAEDGCISTKELGKVMRMLGQNPTPEELQEMI
DEVDEDGSGTVDFDEFLVMMVRCMKDDSKGKSEEELSDLFRMFDKNADGYIDLDELKIML
QATGETITEDDIEELMKDGDKNNDGRIDYDEFLEFMKGVE

Primary citation

The structure of the native cardiac thin filament at systolic Ca 2+ levels. Risi, C.M., Pepper, I., Belknap, B. et al. Proc Natl Acad Sci U S A (2021) 118. DOI 10.1073/pnas.2024288118 · PubMed

Other PDB entries of the same protein (UniProt P68137 (AlphaFold model), which also has an AlphaFold model), best resolution first:

4CBW 2.5 Å, Crystal structure of Plasmodium berghei actin I with D-loop from muscle actin
8EFH 3.3 Å, Helical reconstruction of the human cardiac actin-tropomyosin-myosin complex in complex…
8DD0 3.5 Å, The structure of the native cardiac thin filament junction region
7KO5 7.8 Å, Structure of cardiac native thin filament at pCa=5.8 having upper and lower troponins in…
7KOR 7.8 Å, Structure of cardiac native thin filament at pCa=5.8 having upper troponin in Ca2+ bound…
5NOL 8.0 Å, Ca2+-induced Movement of Tropomyosin on Native Cardiac Thin Filaments - "Closed" state
7TIJ 8.0 Å, Cardiac F-actin decorated with regulatory M-domain of cardiac myosin binding protein C
7TIT 8.0 Å, Cardiac thin filament decorated with regulatory M-domain of cardiac myosin binding…
7TJ7 8.0 Å, Cardiac thin filament decorated with C1 Ig-domain and regulatory M-domain of cardiac…
7KON 8.1 Å, Structure of upper Tn Ca2+ free (rotated) and lower Tn Ca2+ bound cardiac native thin…
7KO7 8.3 Å, Structure of the native cardiac thin filament at pCa=5.8 having upper Tn in Ca2+ free…
5NOG 11.0 Å, Ca2+-induced Movement of Tropomyosin on Native Cardiac Thin Filaments - "Blocked" state

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