Overview
| Uniprot ID | Q19PY3 |
|---|
| Protein Name | RNA-splicing ligase RTCB |
|---|
| Gene Name | RTCB |
|---|
| Organism | Sus scrofa |
|---|
Kla Sites from experimental identification
| Position |
Flanking peptide |
| 17 |
QFLEKINKNCWRIRK |
| 190 |
GYAWAEDKEHCEEYG |
| 206 |
MLQADPNKVSARAKK |
| 285 |
EKAMKRDKIIVNDRQ |
| 366 |
EQHVVDGKERTLLVH |
| 492 |
CHDAGISKKAIKLRP |
| 504 |
LRPIAVIKG****** |
Function
3'-5' RNA ligase, catalytic subunit of the tRNA-splicing ligase complex (tRNA-LC), which is involved in the enzyme-dependent maturation of intron-containing pre-tRNAs. Functions downstream of the tRNA-splicing endonuclease that removes introns, ligating the two generated halves via phosphodiester bond formation. The ligation reaction, which requires guanosine triphosphate (GTP) and Mn(2+), proceeds through three metal-dependent steps. The first step requires ZBTB8OS/Archease and involves the guanylylation of RTCB at its active site histidine, forming a covalent GMP-histidine intermediate. Before the second step, RTCB also hydrolyzes the 2',3'-cyclic phosphate (cP) at the 3' end of the 5' tRNA exon, typically generated by the tRNA-splicing endonuclease, producing a 3' phosphate. The covalently bound GMP is then transferred to this 3' phosphate to form an RNA(3')-P-P-(5')G intermediate. In the final step, the 5'-OH of the 3' exon attacks the activated 3' end of the 5' exon, forming a 3'-5' phosphodiester bond and releasing GMP. RTCB also functions in non-canonical, spliceosome-independent, cytoplasmic splicing of XBP1 mRNAs during the unfolded protein response (UPR). Upon endoplasmic reticulum (ER) stress, the endoribonuclease IRE1/ERN1 excises a short intron, generating free exon ends that are aligned by RNA-intrinsic, zipper-like stem-loop structures. These exon ends are then recognized and ligated by RTCB. This splicing event yields the active XBP1s transcription factor, which induces genes required to resolve protein folding defects in the endoplasmic reticulum
Protein Sequence
10
MSRSYNDELQ
20
FLEKINKNCW
30
RIRKGFVPNM
40
QVEGVFYVND
50
ALEKLMFEEL
60
RNACRGGGVG
70
GFLPAMKQIG
80
NVAALPGIVH
90
RSIGLPDVHS
100
GYGFAIGNMA
110
AFDMNDPEAV
120
VSPGGVGFDI
130
NCGVRLLRTN
140
LDESDVQPVK
150
EQLAQAMFDH
160
IPVGVGSKGV
170
IPMNAKDLEE
180
ALEMGVDWSL
190
REGYAWAEDK
200
EHCEEYGRML
210
QADPNKVSAR
220
AKKRGLPQLG
230
TLGAGNHYAE
240
IQVVDEIFNE
250
YAAKKMGIDH
260
KGQVCVMIHS
270
GSRGLGHQVA
280
TDALVAMEKA
290
MKRDKIIVND
300
RQLACARIAS
310
PEGQDYLKGM
320
AAAGNYAWVN
330
RSSMTFLTRQ
340
AFAKVFNTTP
350
DDLDLHVIYD
360
VSHNIAKVEQ
370
HVVDGKERTL
380
LVHRKGSTRA
390
FPPHHPLIAV
400
DYQLTGQPVL
410
IGGTMGTCSY
420
VLTGTEQGMT
430
ETFGTTCHGA
440
GRALSRAKSR
450
RNLDFQDVLD
460
KLADMGIAIR
470
VASPKLVMEE
480
APESYKNVTD
490
VVNTCHDAGI
500
SKKAIKLRPI
AVIKG
Gene Ontology
| Classification |
GO ID |
Description |
| Cellular Component |
GO:0005737 |
cytoplasm |
| Cellular Component |
GO:0005634 |
nucleus |
| Cellular Component |
GO:0072669 |
tRNA-splicing ligase complex |
| Molecular Function |
GO:0005525 |
GTP binding |
| Molecular Function |
GO:0046872 |
metal ion binding |
| Molecular Function |
GO:0170057 |
RNA ligase (GTP) activity |
| Biological Process |
GO:0006388 |
tRNA splicing, via endonucleolytic cleavage and ligation |
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.