Mutant/mutation
The mutant expresses a C-terminal eGFP-tagged version of serine repeat antigen 1 (SERA1).
(gene model sera 1 in P. yoelii YM: PYYM_0306000)

Protein (function)
Plasmodium species possesses SERAs of two major groups, specified as 'cysteine-type SERAs' and 'serine-type SERAs'. Serine-type SERAs contain an active site serine residue instead of the canonical cysteine residue. The genomes of different Plasmodium species contain different numbers of SERA genes. P. falciparum possesses nine SERA protease genes whereas the P. berghei and P. yoelii genome contains five. P. falciparum possesses six “serine-type” (SERA1 to SERA5 and SERA9) and three “cysteine-type” (SERA6 to SERA8) SERAs. In P. falciparum mutants have been generated lacking expression of SERA1, 2, 3, 4 , 7, 8 and 9 without a distinct phenotype in the blood stages (MvCoubrie J.E. et al,  2007, Infection and Immunity, 75:5565-74).

SERA genes of P. berghei and P. yoelii are arranged in a tandem cluster that contains two serine-type SERAs (PbSERA1, -2) and three cysteine-type SERAs (PbSERA3, -4 and -5). 

Sequence homology and syntenic organisation indicate that PySERA3 (PY000293), -4 (PY02062) and -5 (PY02063) are orthologs of P. falciparum SERA6, (PF3D7_0207500) -7 (PF3D7_0207400), -8 (PF3D7_0207300)

P. yoelii encodes two members of the SERAser subfamily, PySERA1 and PySERA2.
SERA1 (PY00291) and SERA2 (PY00292) previously recognized as SERA3 and a putative cysteine protease respectively.

Phenotype analyses of P. yoelii YM mutants lacling expression of SERA1 indicate that SERA1 does not have an essential role during blood stage development. Growth,multiplication and virulence of blood stages comparable to wild type (WT) parasites although evidence is presented for subtle differences in growth between mutant and WT parasites.

Phenotype
Analyses of mutants expressing eGFP-tagged SERA1 and SERA2 (RMgm-865) it appears that both PySERA1 and 2 are expressed in the later stage of parasite maturation and that the proteases are located insight the parasitophorous vacuole (PV). However, it cannot be ruled out that the observed location in the PV is either due to the GFP tag preventing proper export or due to the fact that SERA are processed at the C-terminal end prior to activation which could result in the GFP tag remaining within the PV while the protease is exported further. However, no obvious free GFP was detected in the parasite schizont extract using anti-GFP antibody.

Additional information
See also below the P. berghei mutants lacking expression of SERA1, SERA2 and lacking both SERA1 and SERA2. These mutants showed a normal growth of blood stages under the conditions tested.

Evidence has been presented that transcription of sera1 and sera2 are upregulated in the lethal YM strain compared to the non-lethal YA strain of P. yoelii.

Other mutants
RMgm-862: A P. yoelii mutant lacking expression of SERA1
RMgm-863: A P. yoelii mutant lacking expression of SERA2
RMgm-864, RMgm-865: Mutants expressing C-terminal GFP-tagged versions of SERA1 and SERA2 respectively

P. berghei mutants:
RMgm-102: A mutant lacking expression of SERA8 (PB000649.01.0; PFB0325c), a cysteine-type SERA homologue (serine repeat antigen 8, SERA-8; ECP1, egress cysteine protease 1; PbSERA5)
RMgm-271: A mutant expressing GFP under the control of the 5'-UTR of PbSERA3 (an ortholog of P. falciparum SERA6)
RMgm-272: The mutant expresses in addition to the endogenous SERA3  (the ortholog of P. falciparum SERA6) a TAP-tagged form of SERA3 under control of its own 5'-UTR and the dhfr/ts 3'-UTR
RMgm-365: A mutant expressing the endogenous SERA1 protein fused to the mCherry red fluorescent protein
RMgm-366: A mutant expressing the endogenous SERA2 protein fused to the mCherry red fluorescent protein
RMgm-368: A knock-out mutant lacking expression of SERA2
RMgm-369: A double knock-out mutant lacking expression of SERA1 and SERA2