Annotations: 4LOS

Domain Annotation: ECOD Classification ECOD Database Homepage

Chains	Family Name	Domain Identifier	Architecture	Possible Homology	Homology	Topology	Family	Provenance Source (Version)
A	CUB	e4losA1	A: beta sandwiches	X: jelly-roll	H: Spermadhesin, CUB domain (From Topology)	T: Spermadhesin, CUB domain	F: CUB	ECOD (1.6)
A	Sushi	e4losA2	A: few secondary structure elements	X: EGF-like	H: EGF-related	T: Complement control module/SCR domain	F: Sushi	ECOD (1.6)

Domain Annotation: CATH CATH Database Homepage

Chain	Domain	Class	Architecture	Topology	Homology	Provenance Source (Version)
A	2.60.120.290	Mainly Beta	Sandwich	Jelly Rolls	Spermadhesin, CUB domain	CATH (4.3.0)
A	2.10.70.10	Mainly Beta	Ribbon	Complement Module	domain 1	CATH (4.3.0)

Protein Family Annotation Pfam Database Homepage

Chains	Accession	Name	Description	Comments	Source
A	PF00084	Sushi repeat (SCR repeat) (Sushi)	Sushi repeat (SCR repeat)		Domain
A	PF00431	CUB domain (CUB)	CUB domain		Domain

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
A	Complement C1s subcomponent heavy chain	cation binding ion binding binding calcium ion binding metal ion binding small molecule binding peptidase activity catalytic activity, acting on a protein serine hydrolase activity serine-type peptidase activity hydrolase activity serine-type endopeptidase activity catalytic activity endopeptidase activity cation binding ion binding binding calcium ion binding metal ion binding small molecule binding peptidase activity catalytic activity, acting on a protein serine hydrolase activity serine-type peptidase activity hydrolase activity serine-type endopeptidase activity catalytic activity endopeptidase activity identical protein binding protein binding	adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains lymphocyte mediated immunity humoral immune response response to stimulus positive regulation of biological process positive regulation of response to stimulus complement activation humoral immune response mediated by circulating immunoglobulin positive regulation of immune response leukocyte mediated immunity regulation of immune system process positive regulation of immune system process complement activation, classical pathway regulation of biological process adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains lymphocyte mediated immunity humoral immune response response to stimulus positive regulation of biological process positive regulation of response to stimulus complement activation humoral immune response mediated by circulating immunoglobulin positive regulation of immune response leukocyte mediated immunity regulation of immune system process positive regulation of immune system process complement activation, classical pathway regulation of biological process immune response biological regulation immunoglobulin mediated immune response adaptive immune response immune effector process regulation of response to stimulus immune system process B cell mediated immunity regulation of immune response activation of immune response biological process involved in interspecies interaction between organisms response to other organism defense response defense response to symbiont response to external stimulus response to biotic stimulus defense response to other organism response to stress innate immune response response to external biotic stimulus proteolysis metabolic process cellular process primary metabolic process protein metabolic process macromolecule metabolic process	cellular anatomical structure extracellular region extracellular space blood microparticle

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
A	IPR009003	Peptidase S1, PA clan	Homologous Superfamily
A	IPR018097	EGF-like calcium-binding, conserved site	Conserved Site
A	IPR001314	Peptidase S1A, chymotrypsin family	Family
A	IPR033116	Serine proteases, trypsin family, serine active site	Active Site
A	IPR035914	Spermadhesin, CUB domain superfamily	Homologous Superfamily
A	IPR001254	Serine proteases, trypsin domain	Domain
A	IPR001881	EGF-like calcium-binding domain	Domain
A	IPR000436	Sushi/SCR/CCP domain	Domain
A	IPR000859	CUB domain	Domain
A	IPR043504	Peptidase S1, PA clan, chymotrypsin-like fold	Homologous Superfamily
A	IPR000152	EGF-type aspartate/asparagine hydroxylation site	PTM
A	IPR024175	Peptidase S1A, complement C1r/C1S/mannan-binding	Family
A	IPR035976	Sushi/SCR/CCP superfamily	Homologous Superfamily

Pharos: Disease Associations Pharos Homepage Annotation

Chains	Drug Target	Associated Disease
A	Pharos: P09871	complement component C1s deficiency Ehlers-Danlos syndrome Hashimoto thyroiditis autoimmune hepatitis autoimmune disease Ehlers-Danlos syndrome, periodontal type 2 Hereditary Angioedema Types I and II esophageal adenocarcinoma subependymal giant cell astrocytoma hereditary angioedema type 2 invasive ductal breast carcinoma adrenal cortex carcinoma limb-girdle muscular dystrophy malignant colon neoplasm chronic kidney disease complement component C1s deficiency Ehlers-Danlos syndrome Hashimoto thyroiditis autoimmune hepatitis autoimmune disease Ehlers-Danlos syndrome, periodontal type 2 Hereditary Angioedema Types I and II esophageal adenocarcinoma subependymal giant cell astrocytoma hereditary angioedema type 2 invasive ductal breast carcinoma adrenal cortex carcinoma limb-girdle muscular dystrophy malignant colon neoplasm chronic kidney disease malignant mesothelioma myopathy diabetes mellitus pancreatic ductal adenocarcinoma Ehlers-Danlos syndrome, periodontal type 1 pancreatic intraductal papillary-mucinous neoplasm with low grade dysplasia psoriasis gastric carcinoma ulcerative colitis head and neck cancer juvenile dermatomyositis angioedema lung cancer malignant ependymoma chronic obstructive pulmonary disease malignant pancreatic neoplasm cystic fibrosis non-small cell lung carcinoma Duchenne muscular dystrophy pancreatic intraductal papillary-mucinous carcinoma pilocytic astrocytoma Emery-Dreifuss muscular dystrophy Sjogren syndrome glioblastoma heart disease large cell medulloblastoma atopic eczema lung carcinoma Becker muscular dystrophy malignant glioma medulloblastoma dermatomyositis ovarian cancer pancreatic intraductal papillary-mucinous neoplasm pituitary cancer

RCSB PDB Core Operations are funded by the U.S. National Science Foundation (DBI-2321666), the US Department of Energy (DE-SC0019749), and the National Cancer Institute, National Institute of Allergy and Infectious Diseases, and National Institute of General Medical Sciences of the National Institutes of Health under grant R01GM157729.