Spätzle (gene)

Spätzle or spaetzle (German for a type of noodle) is an evolutionarily-conserved arthropod protein first identified in Drosophila melanogaster.^[1] It plays a role in embryonic development and in the insect innate immune response. The name was coined by the Nobel laureate Christiane Nüsslein-Volhard after the Spätzle noodle-like form of homozygous mutant fly larvae.^[2]

Spätzle (gene)
Identifiers
Organism	Drosophila melanogaster
Symbol	spz
UniProt	P48607
Search for Structures Swiss-model Domains InterPro

Spätzle
Identifiers
Symbol	Spaetzle
Pfam	PF16077
InterPro	IPR032104
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

Toll signaling pathways in mammals, shrimp and fruit flies

Structure

Spätzle has a cystine knot structure supported by disulfide bridges, is glycosylated, and naturally forms a homodimer. Multiple forms are produced by alternative splicing.^[3] It is produced as a preprotein, and needs to be activated by a serine protease called spätzle-processing enzyme [de]. The signal sequence spz[1-25] is first cleaved, followed by the spz[26-220] fragment, leaving the final spz[221-326] (Spaetzle C-106) part as the mature protein.^[4]

Function

Homodimeric spz binds to a dimeric toll receptor in fruit flies and related organisms, thus activating the signaling cascade.^[5]

Embryonic development

A ligand of the toll pathway, spz is involved in the formation of the dorso-ventral axis in embryonic development. ^[6]