Component of the synapsis initiation complex (SIC) necessary for the synaptonemal complex assembly. Stabilizes the ZIP2 component to the chromosomes. The SIC complex loads onto chromosomes and nucleates ZIP1 polymerization, a molecular zipper that acts to bring homologous chromosomes in close apposition, which is required for meiotic crossover. May also be involved in double strand break repair. Component of the synapsis initiation complex composed of at least ZIP2, ZIP3, MSH4 and MSH5. Interacts also with ZIP1, MRE11, RAD51 and RAD53. Synapsed meiotic chromosomes. Expressed during meiosis.