Key component in the assembly and functioning of vertebrate striated muscles. By providing connections at the level of individual microfilaments, it contributes to the fine balance of forces between the two halves of the sarcomere. The size and extensibility of the cross-links are the main determinants of sarcomere extensibility properties of muscle. In non-muscle cells, seems to play a role in chromosome condensation and chromosome segregation during mitosis. Might link the lamina network to chromatin or nuclear actin, or both during interphase. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Full activation of the protein kinase domain requires both phosphorylation of Tyr-32341, preventing it from blocking the catalytic aspartate residue, and binding of Ca/CALM to the C-terminal regulatory tail of the molecule which results in ATP binding to the kinase. Interacts with MYOM1, MYOM2, tropomyosin and myosin. Interacts with actin, primarily via the PEVK domains and with MYPN (By similarity). Interacts with FHL2, NEB, CRYAB, LMNA/lamin-A and LMNB/lamin-B. Interacts with TCAP/telethonin and/or ANK1 isoform Mu17/ank1.5, via the first two N-terminal immunoglobulin domains. Interacts with TRIM63 and TRIM55, through several domains including immunoglobulin domains 141 and 142. Interacts with ANKRD1, ANKRD2 and ANKRD23, via the region between immunoglobulin domains 77 and 78 and interacts with CAPN3, via immunoglobulin domain 79. Interacts with NBR1 through the protein kinase domain. Interacts with CALM/calmodulin. Isoform 6 interacts with OBSCN isoform 3. Interacts with CMYA5. A number of isoforms may be produced, ranging from 27000 to 33000 residues in different striated muscle tissues, the size of the full-length protein may be up to 38138 residues. Isoforms 3, 7 and 8 are expressed in cardiac muscle. Isoform 4 is expressed in vertebrate skeletal muscle. Isoform 6 is expressed in skeletal muscle (at protein level). ZIS1 and ZIS5 regions contain multiple SPXR consensus sites for ERK- and CDK-like protein kinases as well as multiple SP motifs. ZIS1 could adopt a closed conformation which would block the TCAP-binding site. The PEVK region may serve as an entropic spring of a chain of structural folds and may also be an interaction site to other myofilament proteins to form interfilament connectivity in the sarcomere. Autophosphorylated. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. In some isoforms, after the PEVK repeat region there is a long PEVK duplicated region. On account of this region, it has been very difficult to sequence the whole protein. The length of this region (ranging from 183 to 2174 residues), may be a key elastic element of titin. Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. Contaminating sequence. Potential poly-A sequence starting in position 553. Contaminating sequence. Potential poly-A sequence starting in position 627. Titin entry