Overview
| Uniprot ID | Q52NJ3 |
|---|
| Protein Name | Small COPII coat GTPase SAR1A |
|---|
| Gene Name | SAR1A |
|---|
| Organism | Sus scrofa |
|---|
Kla Sites from experimental identification
| Position |
Flanking peptide |
| 146 |
TDAISEEKLREIFGL |
| 166 |
GKGNVTLKELNARPM |
| 46 |
TTLLHMLKDDRLGQH |
Function
Small GTPase that cycles between an active GTP-bound and an inactive GDP-bound state and mainly functions in vesicle-mediated endoplasmic reticulum (ER) to Golgi transport. The active GTP-bound form inserts into the endoplasmic reticulum membrane where it recruits the remainder of the coat protein complex II/COPII. The coat protein complex II assembling and polymerizing on endoplasmic reticulum membrane is responsible for both the sorting of cargos and the deformation and budding of membranes into vesicles destined to the Golgi. The GTPase activity of SAR1 by controlling the timing of COPII budding regulates the size of the formed vesicles and is important for cargo selection depending on their size. Together with SEC16A, forms the organized scaffold defining endoplasmic reticulum exit sites (ERES), some specific domains of the endoplasmic reticulum where COPII vesicles form. In addition to its role in vesicle trafficking, can also function as a leucine sensor regulating TORC1 signaling and more indirectly cellular metabolism, growth and survival. In absence of leucine, interacts with the GATOR2 complex via MIOS and inhibits TORC1 signaling. The binding of leucine abrogates the interaction with GATOR2 and the inhibition of the TORC1 signaling. This function is completely independent of the GTPase activity of SAR1B
Protein Sequence
10
MSFIFEWIYN
20
GFSSVLQFLG
30
LYKKSGKLVF
40
LGLDNAGKTT
50
LLHMLKDDRL
60
GQHVPTLHPT
70
SEELTIAGMT
80
FTTFDLGGHE
90
QARRVWKNYL
100
PAINGIVFLV
110
DCADHPRLME
120
SKVELNALMT
130
DETISNVPIL
140
ILGNKIDRTD
150
AISEEKLREI
160
FGLYGQTTGK
170
GNVTLKELNA
180
RPMEVFMCSV
190
LKRQGYGEGF
RWLSQYID
Gene Ontology
| Classification |
GO ID |
Description |
| Molecular Function |
GO:0046872 |
metal ion binding |
| Biological Process |
GO:1990253 |
cellular response to leucine starvation |
| Biological Process |
GO:0048208 |
COPII vesicle coating |
| Biological Process |
GO:0090110 |
COPII-coated vesicle cargo loading |
| Biological Process |
GO:0006888 |
endoplasmic reticulum to Golgi vesicle-mediated transport |
| Biological Process |
GO:0006886 |
intracellular protein transport |
| Biological Process |
GO:0061024 |
membrane organization |
| Biological Process |
GO:1904262 |
negative regulation of TORC1 signaling |
| Biological Process |
GO:0003400 |
regulation of COPII vesicle coating |
| Biological Process |
GO:0016050 |
vesicle organization |
| Cellular Component |
GO:0030127 |
COPII vesicle coat |
| Cellular Component |
GO:0005829 |
cytosol |
| Cellular Component |
GO:0070971 |
endoplasmic reticulum exit site |
| Cellular Component |
GO:0005789 |
endoplasmic reticulum membrane |
| Cellular Component |
GO:0032580 |
Golgi cisterna membrane |
| Cellular Component |
GO:0005765 |
lysosomal membrane |
| Molecular Function |
GO:0140785 |
amino acid sensor activity |
| Molecular Function |
GO:0003925 |
G protein activity |
| Molecular Function |
GO:0005525 |
GTP binding |
| Molecular Function |
GO:0003924 |
GTPase activity |
Reference
[1] Fan S, Zhou R, Wen H, Ye H, Ma S et al.. Global profiling of protein lactylome in porcine granulosa cells.. J Ovarian Res 18(1):177. 2025 Aug 8. PMID: 40781717.