Fig. 1

Meiosis telomere complex in M. musculus and S. pombe.a Schematic representation of the interacting domains mediating the simultaneous binding of TERB1-TERB2-MAJIN and telomeric shelterin protein TRF1. The MAJIN C-terminus contains a transmembrane binding domain (TM, aa 232–251) and interacts via its N-terminal domain (NTD, aa 1–120) with a specific C-terminal domain of TERB2 (CTD, aa 169–202). The TERB2 N-terminal domain (NTD, aa 2–194) interacts with the C-terminal domain of TERB1 (T2B, aa 593–622), encompassed by the TRF1-binding domain (TRFB, aa 523–699) which in turn interacts with the TRF homology domain of TRF1 (TRFH, aa 54–251). The TERB1 N-terminus contains an armadillo repeat (ARM repeat, aa 16–384) domain that is thought to interact with the SUN1/2. Both TERB1 and TRF1 also possess a MYB domain (MYB, aa 715–747; aa 367–416 respectively) that binds double-stranded telomeric DNA. The TERB1 MYB domain also interacts with the meiotic cohesin subunit SA3. b Molecular components involved in meiotic telomere attachment and movement through the nuclear envelope (NE) in S. pombe and M. musculus. The highly conserved LINC complex is composed of the SUN domain protein in the inner nuclear envelope (INM) and interacts in the perinuclear space with a KASH domain protein localized in the outer nuclear envelope (ONM). The LINC complex functions to connect the telomeres indirectly with cytoplasmic microtubules by the molecular linker dynein. Sad1-Kms1/2 and SUN1/2-KASH5 represents the LINC complex in S. pombe and M. musculus respectively. The association of telomeres to the NE requires meiosis-specific telomere adaptor proteins that bridge the interaction between the telomere sheltering complex and the LINC complex. In S. pombe shelterin-related proteins Rap1-Taz1 interact with meiosis-specific telomere protein Bqt1–2 to associate with Sad1. The ubiquitously expressed INM Bqt3–4 proteins also assist the interaction of telomeres to the NE through the association of Bqt4-Rap1. In mouse TERB1-TERB2-MAJIN meiotic telomere complex interact with TRF1 telomere shelterin protein and with SUN1/2. MAJIN protein has DNA binding properties and a single transmembrane domain similarly to the S. pombe Bqt4 protein. c Comparable components responsible of the meiotic telomere attachment and chromosome movements between S. pombe and M. musculus