| Summary: | 碩士 === 國立臺灣大學 === 微生物與生化學研究所 === 93 === Four AtMAPRs (AtMAPR2, AtMAPR3, AtMPAR4, and AtMAPR5) sharing 30-
40% similarity with porcine MAPR (membrane associated progesterone receptor
component 1) have been identified in Arabidopsis. The function of the four AtMAPRs is
not clear, but we speculated that they could participate in regulating environmental
stimuli such as plant hormones, light, or stresses. Previous yeast two-hybrid assay
indicated that AtMAPRs might interact with polyubiquitin, MYB3 transcription factor,
AtTOC33 (GTP-binding protein), and AGT1 (alanine-glyoxylate aminotransferase).
However, the presence of putative transmembrane domain of AtMAPR3, AtMAPR4, and
AtMAPR5 might interfere with yeast two-hybrid results. In this work, we used truncated
AtMAPR5, lacking the 1-40 amino acid residues, as bait to screen flower two-hybrid
cDNA library, CD4-30. Among the 26 different interacting proteins obtained from the
screening, a C3HC4-type RING protein (At3g58030) and a FKBP-type peptidyl-prolyl
cis-trans isomerase, AtFKBP16-2 (At4g39710) was perhaps to function together with
AtMAPR5 in Arabidopsis. We proposed two models based on these two interacting
proteins that: (1) C3HC4-type RING protein might function as E3 ligase and promote the
degradation of AtMAPRs. (2) AtMAPRs might be involved in electron transferring in
photosynthesis with AtFKBP16-2. Further work has to be done to testify these two
assumptions. Briefly, these yeast two-hybrid results provided hints to the function of
AtMAPRs.
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