Involved in neural development, regulating the establishment of proper connectivity within the nervous system. Plays a role in the establishment of the anterior-posterior axis during gastrulation. Regulates the differentiation and cellular process formation of oligodendrocytes and myelination of small-diameter axons in the central nervous system (CNS). Promotes activation of focal adhesion kinase. May function as a cellular signal transducer. Homodimer; disulfide-linked. May also form heterodimer with either TENM1 or TENM2 or TENM3. Additional mRNAs also exist. Tissue-specific expression of isoforms was observed throughout embryogenesis and in the brain and ovary adult tissues. Expressed in brain and spinal cord (at protein level). Expressed in neurons and oligodendrocytes of the spinal cord. Expressed weakly in kidney, lung and spleen. Expressed in the cortex, CA1, CA2 and CA3 of the hippocampus. Expressed in the white matter, Purkinje cells and molecular layer of the cerebellum. Expressed in spinal cord at 18 dpc (at protein level). Expressed in the epiblast and extraembryonic regions as early as 6.5 dpc. Expressed in the neural plate and extraembryonic tissues at 7.5 dpc. Expressed in the forebrain, mid/hindbrain junction, somites and tail bud at 8.5 dpc. Expressed in the tail bud and limbs at 11.5 dpc. Expressed in the diencephalon and midbrain at 12.5 dpc. Up-regulated during oligodendrocyte differentiation. EGF-like domains 2 and 5 which have an odd number of cysteines might enable the formation of intermolecular disulfide bonds. Cytoplasmic proline-rich regions could serve as docking domains for intracellular SH3-containing proteins. Mice show tremors and hypomyelination in the central nervous system (CNS), particularly in the spinal cord, but not in the sciatic nerve of the peripheral nervous system (PNS). Differentiation of oligodendrocytes is prevented in the spinal cord. Belongs to the tenascin family. Teneurin subfamily.