Structural maturation of SYCP1-mediated meiotic chromosome synapsis by SYCE3.
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SYCE3 actively remodels SYCP1 tetramer lattice during early synapsis, not just stabilizes it
"SYCE3 has an essential role in actively remodelling SYCP1 tetramer lattices during the early stages of synapsis"
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SYCE3 binds SYCP1 tetrameric core (alphaNcore) with approximately 170 nM affinity
"indicated a binding affinity of 170 ± 30 nM"
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SYCE3 binding converts SYCP1 tetramers to 2:1 SYCP1-SYCE3 heterotrimers
"SYCP1 tetramers undergo conformational change into 2:1 heterotrimers on SYCE3 binding, removing their assembly interfaces and disrupting the SYCP1 lattice"
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SYCE3 self-assembly provides tetramer-like interfaces for integrated SYCP1-SYCE3 lattice
"SYCE3 then establishes a new lattice by its self-assembly mimicking the role of the disrupted interface in tethering together SYCP1 dimers"
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SYCE3 W41E/Y44E mutation blocks lateral self-assembly and integrated lattice formation
"The SYCE3 WY mutation separates the disruptive and integrative functions of SYCE3, triggering SYCP1 tetramer lattice disruption, whilst failing to form an integrated SYCP1-SYCE3 lattice"
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Syce3WY/WY mice are infertile with severely disrupted SYCP1 assemblies
"Syce3WY/WY and Syce3Δ/Δ homozygotes exhibited severely reduced testis weights and epididymal sperm counts, with testis histology indicating a severe block in meiosis"
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Syce3 null mice retain SYCP1 tetramer lattices but cannot form mature SC
"Syce3Δ/Δ captures the formation of SYCP1 tetramer lattices between axes, which cannot be remodelled in absence of SYCE3, so fail to develop into a mature SC"
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SYCE3 recruits SYCE1-SIX6OS1 and SYCE2-TEX12 complexes (micromolar affinity)
"SYCE3 remodels and integrates into the SYCP1 lattice, establishing binding sites that cooperativity recruit SYCE1-SIX6OS1 and SYCE2-TEX12"
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SYCE3 promotes fibrous assembly of SYCE2-TEX12
"SYCE3 promoted fibrous assembly of SYCE2-TEX12"