Literature summary for 3.6.5.4 extracted from

Wild, K.; Bange, G.; Motiejunas, D.; Kribelbauer, J.; Hendricks, A.; Segnitz, B.; Wade, R.C.; Sinning, I.
Structural basis for conserved regulation and adaptation of the signal recognition particle targeting complex (2016), J. Mol. Biol., 428, 2880-2897 .

Search for more literature for 3.6.5.4

Crystallization (Commentary)

Crystallization (Comment)	Organism
SRalpha and SRbeta complex, X-ray diffraction structure determination and analysis	Canis lupus familiaris

Protein Variants

Protein Variants	Comment	Organism
D181N	site-directed mutagenesis of SRP54 (or SRbeta), the mutant shows the wild-type phenotype and binding of SRalpha at wild-type level, but no binding in absence of GTP. SRalpha binding to D181N can be restored to some level by adding back nucleotide, i.e. GTP, GDP, XTP or XDP, but not with ATP	Canis lupus familiaris
G118L	site-directed mutagenesis of SRP54 (or SRbeta), the mutant shows a temperature-sensitive phenotype and binding of SRalpha at wild-type level	Canis lupus familiaris
G118L/D181N	site-directed mutagenesis of SRP54 (or SRbeta) and weak binding of SRalpha	Canis lupus familiaris
H119L	site-directed mutagenesis of SRP54 (or SRbeta), the mutant shows the wild-type phenotype and binding of SRalpha at wild-type level	Canis lupus familiaris
K75I	site-directed mutagenesis of SRP54 (or SRbeta), the mutant shows a temperature-sensitive phenotype and no binding of SRalpha	Canis lupus familiaris
K75I/H119L	site-directed mutagenesis of SRP54 (or SRbeta), the mutant shows a null mutant phenotype and no binding of SRalpha	Canis lupus familiaris
additional information	construction of several deletion mutants: SRbeta-DELTATM, SRbetaDELTA4, SRbetaDELTA5, SRbeta1C1-DELTATM, SRbeta-DELTAloop, and SRbeta-loop2, phenotypes, altered SRalpha binding of the truncated mutants, overview. Deletion of the last 6 amino-acids from the carboxyl-terminus of the SRbeta GTPase domain results in a molecule (SRbetaC1) with primarily type I topology, similar to SRbeta	Canis lupus familiaris
N178K	site-directed mutagenesis of SRP54 (or SRbeta), the mutant shows a temperature-sensitive phenotype and weak binding of SRalpha	Canis lupus familiaris

Localization

Localization	Comment	Organism	GeneOntology No.	Textmining
endoplasmic reticulum membrane	peripheral membrane SRalpha subunit, the transmembrane SRbeta subunit is anchoring SRalpha on the endoplasmic reticulum membrane	Canis lupus familiaris	5789	-
membrane	peripheral membrane SRalpha subunit, the transmembrane SRbeta subunit is anchoring SRalpha on the endoplasmic reticulum membrane	Canis lupus familiaris	16020	-
additional information	the domain of SRalpha that binds SRbeta does so by binding directly to the nucleotide bound form of the GTPase domain of SRbeta. Additional level of regulation of SRP receptor function based on regulated dissociation of the receptor subunits	Canis lupus familiaris	-	-

Metals/Ions

Metals/Ions	Comment	Organism	Structure
Mg2+	required	Canis lupus familiaris

Natural Substrates/ Products (Substrates)

Natural Substrates	Organism	Comment (Nat. Sub.)	Natural Products	Comment (Nat. Pro.)	Rev.	Reac.
GTP + H2O	Canis lupus familiaris	-	GDP + phosphate	-	?

Organism

Organism	UniProt	Comment	Textmining
Canis lupus familiaris	P61010 AND P06625	subunits SRP54 (or SRbeta) and SRalpha	-

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
GTP + H2O	-	Canis lupus familiaris	GDP + phosphate	-	?

Subunits

Subunits	Comment	Organism
heterodimer	the signal recognition particle (SRP) receptor is a heterodimer of two polypeptides (SRalpha and SRbeta) that each contain a GTP binding domain. The GTP binding domain in the peripheral membrane SRalpha subunit has a well defined role in regulating targeting of SRP ribosome-nascent chain complexes to the translocon. Without bound GTP, the empty form of the SRbeta GTPase domain is unable to dimerize with SRalpha	Canis lupus familiaris
More	determination of the crystal structure of the GTPase heterodimers, and structure comparisons, overview	Canis lupus familiaris

Synonyms

Synonyms	Comment	Organism
SR	-	Canis lupus familiaris
SRP GTPase	-	Canis lupus familiaris

General Information

General Information	Comment	Organism
malfunction	deletion of the N-terminal transmembrane domain of SRbeta does not effect receptor dimerization but reveals a cryptic translocation signal that overlaps the GTPase domain. Deletion of the G-1 region, (SRbetaD5) which comprises part of the SRbeta GTPase domain, abolishes binding to SRalpha. A mutant SRbeta containing an amino acid substitution allows the GTPase domain to bind XTP dimerizes with SRalpha most efficiently in the presence of XTP or XDP, but not ATP	Canis lupus familiaris
additional information	analysis of binding of wild-type and mutant SRalpha and SRbeta by gel filtration and immunoprecipitation, overview. SRX2, the minimum SRbeta binding domain of SRalpha, binds to the GTPase domain of SRbeta, no other regions of SRalpha are observed to bind to SRbeta. Structural basis for conserved regulation and adaptation of the signal recognition particle targeting complex, overview	Canis lupus familiaris
physiological function	the signal recognition particle (SRP) is a ribonucleoprotein complex with a key role in targeting and insertion of membrane proteins. The two SRP GTPases, SRP54 (Ffh in bacteria) and FtsY (SRalpha in eukaryotes), form the core of the targeting complex (TC) regulating the SRP cycle. The architecture of the TC and its stimulation by RNA has been described for the bacterial SRP system while this information is lacking for other domains of life	Canis lupus familiaris

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Release 2023.1 (January 2023)