GPI-anchor transamidase (GPI transamidase) (EC 3.-.-.-) (GPI8 homolog) (hGPI8) (Phosphatidylinositol-glycan biosynthesis class K protein) (PIG-K)
1_MAVTD 6_ SLSRA 11_ ATVLA 16_ TVLLL 21_ SFGSV 26_ AASHI 31_ EDQAE 36_ QFFRS 41_ GHTNN 46_ WAVLV 51_ CTSRF 56_ WFNYR 61_ HVANT 66_ LSVYR 71_ SVKRL 76_ GIPDS 81_ HIVLM 86_ LADDM 91_ ACNPR 96_ NPKPA 101_ TVFSH 106_ KNMEL 111_ NVYGD 116_ DVEVD 121_ YRSYE 126_ VTVEN 131_ FLRVL 136_ TGRIP 141_ PSTPR 146_ SKRLL 151_ SDDRS 156_ NILIY 161_ MTGHG 166_ GNGFL 171_ KFQDS 176_ EEITN 181_ IELAD 186_ AFEQM 191_ WQKRR 196_ YNELL 201_ FIIDT 206_ CQGAS 211_ MYERF 216_ YSPNI 221_ MALAS 226_ SQVGE 231_ DSLSH 236_ QPDPA 241_ IGVHL 246_ MDRYT 251_ FYVLE 256_ FLEEI 261_ NPASQ 266_ TNMND 271_ LFQVC 276_ PKSLC 281_ VSTPG 286_ HRTDL 291_ FQRDP 296_ KNVLI 301_ TDFFG 306_ SVRKV 311_ EITTE 316_ TIKLQ 321_ QDSEI 326_ MESSY 331_ KEDQM 336_ DEKLM 341_ EPLKY 346_ AEQLP 351_ VAQII 356_ HQKPK 361_ LKDWH 366_ PPGGF 371_ ILGLW 376_ ALIIM 381_ VFFKT 386_YGIKH
1: Catalytic subunit of the glycosylphosphatidylinositol-anchor (GPI-anchor) transamidase (GPI-T) complex that catalyzes the formation of the linkage between a proprotein and a GPI-anchor and participates in GPI anchored protein biosynthesis (PubMed:10793132, PubMed:11483512, PubMed:12582175, PubMed:34576938, PubMed:35165458, PubMed:35551457, PubMed:37684232, PubMed:9356492). Recognizes diverse proproteins at a C-terminal signal peptide (CSP) region that lacks consensus sequence and replaces it with a GPI-anchor via a transamidation reaction (PubMed:35165458, PubMed:35551457, PubMed:37684232). Transamidation catalysis reaction follows a two-phase mechanism (PubMed:37684232). In the acyl-enzyme phase, the carbonyl group of the proproteins's omega-site undergoes a nucleophilic attack forming an enzyme-substrate thioester bond (PubMed:37684232). Followed by a general acid catalysis that allows CSP releasing, regenerating the carbonyl, and forming the acyl-enzyme intermediate (PubMed:37684232). In the GPI-anchor attachment phase, the amino group of the GPI-anchor's ethanolamine phosphate, the one on third mannose (EtNP3), mediates a nucleophilic attack on the carbonyl of the acyl-enzyme intermediate, replacing the CSP, allowing GPI-anchor attachment to the omega-residue, therefore forming the product and freeing the enzyme (PubMed:37684232)