PDBx/mmCIF category	Legacy PDB format records	Description
_atom_site	ATOM HETATM	Details about the atoms in a macromolecular crystal structure, such as the positional coordinates, temperature factors, and occupancies.

Notes:

• _atom_site.label_asym_id - ASYM ID, a unique and sequential identifier of each molecule (starting from letter A) in the model. This data item is a pointer to _struct_asym.id in the _struct_asym category.
  • ASYM_ID can be different from the author provided (or PDB assigned) chain identifier (Chain ID), ASYM_ID is assigned sequentially starting from letter A to all polymer and non-polymer molecule instances in the structure.
  • All water molecules are assigned one ASYM_ID.
• _atom_site.auth_asym_id - author provided (or PDB assigned) Chain ID.
• _atom_site.label_entity_id - a unique identifier of all unique polymer and non-polymer molecules in the structure as it is referred to in the _entity category.
• _atom_site.label_comp_id - PDB assigned residue name.
• _atom_site.auth_comp_id - author provided or PDB assigned residue name.
• _atom_site.label_seq_id - unique and sequential residue number (starting from 1 including unmodeled residues) in the polymer sequence.
• _atom_site.auth_seq_id - author provided residue number.

Example:

loop_
_atom_site.group_PDB
_atom_site.id
_atom_site.type_symbol
_atom_site.label_atom_id
_atom_site.label_alt_id
_atom_site.label_comp_id
_atom_site.label_asym_id
_atom_site.label_entity_id
_atom_site.label_seq_id
_atom_site.pdbx_PDB_ins_code
_atom_site.Cartn_x
_atom_site.Cartn_y
_atom_site.Cartn_z
_atom_site.occupancy
_atom_site.B_iso_or_equiv
_atom_site.pdbx_formal_charge
_atom_site.auth_seq_id
_atom_site.auth_comp_id
_atom_site.auth_asym_id
_atom_site.auth_atom_id
_atom_site.pdbx_PDB_model_num
ATOM	1	N	N	.	MET	A	1	1	?	10.121	49.201	18.054	1.00	88.02	?	40	MET	A	N	1
ATOM	2	C	CA	.	MET	A	1	1	?	8.837	48.574	18.359	1.00	85.54	?	40	MET	A	CA	1
ATOM	3	C	C	.	MET	A	1	1	?	7.968	48.387	17.110	1.00	78.31	?	40	MET	A	C	1
ATOM	4	O	O	.	MET	A	1	1	?	6.906	47.764	17.17	1.00	77.36	?	40	MET	A	O	1
ATOM	5	C	CB	.	MET	A	1	1	?	8.081	49.393	19.407	1.00	91.19	?	40	MET	A	CB	1
ATOM	6	C	CG	.	MET	A	1	1	?	8.647	49.264	20.815	1.00	97.92	?	40	MET	A	CG	1
ATOM	7	S	SD	.	MET	A	1	1	?	8.520	47.577	21.459	1.00	99.09	?	40	MET	A	SD	1
ATOM	8	C	CE	.	MET	A	1	1	?	10.226	47.245	21.909	1.00	96.88	?	40	MET	A	CE	1
ATOM	9	N	N	.	GLY	A	1	2	?	8.409	48.936	15.983	1.00	64.64	?	41	GLY	A	N	1
ATOM	10	C	CA	.	GLY	A	1	2	?	7.802	48.609	14.715	1.00	44.08	?	41	GLY	A	CA	1
ATOM	11	C	C	.	GLY	A	1	2	?	8.184	47.194	14.310	1.00	37.87	?	41	GLY	A	C	1
ATOM	12	O	O	.	GLY	A	1	2	?	8.744	46.415	15.082	1.00	32.33	?	41	GLY	A	O	1
ATOM	13	N	N	.	LEU	A	1	3	?	7.868	46.866	13.059	1.00	29.81	?	42	LEU	A	N	1
ATOM	14	C	CA	.	LEU	A	1	3	?	8.194	45.563	12.503	1.00	26.22	?	42	LEU	A	CA	1
..... (truncated for brevity)
HETATM	7475	O	O1	.	GOL	F	3	.	?	12.399	17.309	2.493	1.00	49.81	?	302	GOL	A	O1	1
HETATM	7476	C	C2	.	GOL	F	3	.	?	11.119	19.504	2.235	1.00	58.42	?	302	GOL	A	C2	1
HETATM	7477	O	O2	.	GOL	F	3	.	?	11.275	19.672	0.870	1.00	52.72	?	302	GOL	A	O2	1
HETATM	7478	C	C3	.	GOL	F	3	.	?	11.147	20.886	2.974	1.00	60.69	?	302	GOL	A	C3	1
HETATM	7479	O	O3	.	GOL	F	3	.	?	11.560	21.902	2.108	1.00	56.04	?	302	GOL	A	O3	1
..... (truncated for brevity)
HETATM	7536	O	O	.	HOH	P	5	.	?	-0.397	5.714	-2.954	1.00	55.09	?	401	HOH	A	O	1
HETATM	7537	O	O	.	HOH	P	5	.	?	1.933	22.895	0.037	1.00	41.11	?	402	HOH	A	O	1
HETATM	7538	O	O	.	HOH	P	5	.	?	18.942	20.641	12.691	1.00	35.07	?	403	HOH	A	O	1
HETATM	7539	O	O	.	HOH	P	5	.	?	-0.984	8.117	1.053	1.00	44.71	?	404	HOH	A	O	1
HETATM	7540	O	O	.	HOH	P	5	.	?	-0.000	-0.000	-4.882	0.50	38.73	?	405	HOH	A	O	1
HETATM	7541	O	O	.	HOH	P	5	.	?	6.821	7.758	19.352	1.00	65.84	?	406	HOH	A	O	1
HETATM	7542	O	O	.	HOH	P	5	.	?	6.505	18.912	6.900	1.00	43.17	?	407	HOH	A	O	1
HETATM	7543	O	O	.	HOH	P	5	.	?	-4.255	12.564	-7.163	1.00	53.88	?	408	HOH	A	O	1

PDBx/mmCIF category	Legacy PDB format records	Description
_atom_site_anisotrop	ANISOU	Details about the anisotropic displacement parameters.

Notes:

• Represent elements of the standard anisotropic atomic displacement matrix U, which appears in the structure-factor term as:
  • T = exp{-2 pi² sum_i[sum_j(U^ij h_i h_j a_i^* a_j^*)]}
  • h = the Miller indices
  • a^* = the reciprocal space cell lengths
• In the legacy PDB format files the same anisotropic temperature factors are scaled by a factor of 10⁴ (Angstroms²) and are presented as integers.

Example:

loop_
_atom_site_anisotrop.id
_atom_site_anisotrop.type_symbol
_atom_site_anisotrop.pdbx_label_atom_id
_atom_site_anisotrop.pdbx_label_alt_id
_atom_site_anisotrop.pdbx_label_comp_id
_atom_site_anisotrop.pdbx_label_asym_id
_atom_site_anisotrop.pdbx_label_seq_id
_atom_site_anisotrop.pdbx_PDB_ins_code
_atom_site_anisotrop.U[1][1]
_atom_site_anisotrop.U[2][2]
_atom_site_anisotrop.U[3][3]
_atom_site_anisotrop.U[1][2]
_atom_site_anisotrop.U[1][3]
_atom_site_anisotrop.U[2][3]
_atom_site_anisotrop.pdbx_auth_seq_id
_atom_site_anisotrop.pdbx_auth_comp_id
_atom_site_anisotrop.pdbx_auth_asym_id
_atom_site_anisotrop.pdbx_auth_atom_id
1	N	N	.	MET	A	1	?	1.2107	1.0696	1.0693	0.0076	-0.0422	-0.3059	40	MET	A	N
2	C	CA	.	MET	A	1	?	1.1724	1.0654	1.0125	0.0219	-0.0147	-0.3086	40	MET	A	CA
3	C	C	.	MET	A	1	?	1.0644	0.9574	0.9537	0.0404	-0.0040	-0.2902	40	MET	A	C
4	O	O	.	MET	A	1	?	1.0413	0.9680	0.9301	0.0495	0.0180	-0.2876	40	MET	A	O
5	C	CB	.	MET	A	1	?	1.2482	1.1430	1.0736	0.0301	-0.0016	-0.3458	40	MET	A	CB
6	C	CG	.	MET	A	1	?	1.3496	1.2585	1.1122	0.0134	-0.0061	-0.3622	40	MET	A	CG
7	S	SD	.	MET	A	1	?	1.3676	1.3267	1.0707	0.0023	0.0074	-0.3342	40	MET	A	SD
8	C	CE	.	MET	A	1	?	1.3559	1.3081	1.0171	-0.0205	-0.0277	-0.3192	40	MET	A	CE
9	N	N	.	GLY	A	2	?	0.8894	0.7460	0.8208	0.0436	-0.0202	-0.2751	41	GLY	A	N
10	C	CA	.	GLY	A	2	?	0.6158	0.4733	0.5858	0.0581	-0.0157	-0.2497	41	GLY	A	CA
11	C	C	.	GLY	A	2	?	0.5329	0.4169	0.4891	0.0499	-0.0142	-0.2242	41	GLY	A	C
12	O	O	.	GLY	A	2	?	0.4693	0.3760	0.3830	0.0353	-0.0147	-0.2254	41	GLY	A	O
..... (truncated for brevity)