Ubiquitin E3 ligase that acts as a limiting factor for crossing-over during meiosis: required during zygonema to limit the colocalization of RNF212 with MutS-gamma-associated recombination sites and thereby establish early differentiation of crossover and non-crossover sites. Later, it is directed by MutL-gamma to stably accumulate at designated crossover sites. Probably promotes the dissociation of RNF212 and MutS-gamma to allow the progression of recombination and the implementation of the final steps of crossing over. Modulates cyclin-B levels and participates in the regulation of cell cycle progression through the G2 phase. Overexpression causes delayed entry into mitosis. S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. Protein modification; protein ubiquitination. Interacts with CCNB1, UBE2L3 and NF2. Associates to the synaptonemal complex. Expressed predominantly in the testes and 17 day embryos (corresponding to prophase I in females). Weakly or not expressed in other tissues. In spermatocytes, synaptonemal complex-associated Ccnb1ip1 foci are detected by early pachynema and their number peaks during midpachynema. In late-pachytene nuclei, Ccnb1ip1 foci number descrease. At the onset of diplonema, foci are no longer detected (at protein level). Ubiquitinated; autoubiquitinated. Phosphorylated by CDK1 on serine or threonine residues (in vitro). Both male and female mice are sterile. Males do not make sperm and have much smaller testes, a characteristic of mutants with meiotic defects. Early stages of meiosis occur normally and full synapsis of homologous chromosomes (homologs) is achieved. However, crossover-specific recombination complexes do not assemble and crossing-overs fail. In spermatocytes, chromosomes fail to congress properly at the metaphase plate, leading to arrest and apoptosis before the first meiotic division. Mutant oocytes have a similar chromosomal phenotype but can undergo meiotic divisions and fertilization before arresting. During late meiotic prophase males, absence of Cdk2 and mismatch repair protein association from chromosome cores is correlated with the premature separation of bivalents at diplonema owing to lack of chiasmata.