biostudies-literatureGreenman ACNHLBI NIH HHS82-92https://www.ebi.ac.uk/biostudies/studies/S-EPMC11963209biostudies-literatureUnknown200Cardiac myosin binding protein-C (cMyBP-C) is a sarcomere regulatory protein consisting of 11 well-folded immunoglobulin-like (Ig-like) and fibronectin type-III domains with the individual domains numbered C0-C10. Despite progress in understanding the functions of the N' and C'-terminal ends of the protein, our understanding of the functional effects of the middle domains (C3-C4-C5-C6-C7) is still limited. Here we aimed to determine the functional significance of the middle domains by replacing endogenous cMyBP-C with recombinant proteins with and without the middle domains using our "cut and paste" SpyC3 mouse model. Specifically, we deleted domains C3-C7 or substituted these domains with unrelated Ig-like domains from titin to behave as inert "spacer" domains. Replacement with the spacerJournal of molecular and cellular cardiologyAutoinhibition of cMyBP-C by its middle domains.PMC11963209F32 HL170509R01 HL140925R01 HL080367Greenman ACHarris SPSadler RLfalseAutoinhibition of cMyBP-C by its middle domains.Cardiac myosin binding protein-C (cMyBP-C) is a sarcomere regulatory protein consisting of 11 well-folded immunoglobulin-like (Ig-like) and fibronectin type-III domains with the individual domains numbered C0-C10. Despite progress in understanding the functions of the N' and C'-terminal ends of the protein, our understanding of the functional effects of the middle domains (C3-C4-C5-C6-C7) is still limited. Here we aimed to determine the functional significance of the middle domains by replacing endogenous cMyBP-C with recombinant proteins with and without the middle domains using our "cut and paste" SpyC3 mouse model. Specifically, we deleted domains C3-C7 or substituted these domains with unrelated Ig-like domains from titin to behave as inert "spacer" domains. Replacement with the spacer2025-01-01T00:00:00Z2025 Mar2026-07-16T23:19:57.914Z2026-07-12T03:11:10.428ZS-EPMC119632093992398710.1016/j.yjmcc.2025.02.002