The gene starts at 73136092 bp from pter and ends at 73174790 bp from pter. Its size is 38699 bases and its orientation lie in the plus strand. The 5 promoter region (1.5 kb) contains putative sites for transcriptional regulation including Sp1, MZF1, AP1 and NF-E2. No consensus TATA box is evident.

The transcript contains 16 exons spanning a length of 3.332 kb. The mRNA contains a short 5UTR but a long 3 end UTR. Two LIM domains, LIM1 and LIM2 are encoded by the exons 2-4. A single PDZ domain is encoded by the exons 2-6. A C-terminal domain is encoded by exons 8-16.

None identified.

The LIMK1 protein is composed of 647 amino acids. It belongs to a unique family of LIM domain containing dual specificity (serine threonine and tyrosine) protein kinase. LIMK1 also has a PDZ domain in the middle of the gene and a kinase domain at the C-terminal end. A stretch of basic amino acids resembling nuclear localisation signal is present in the kinase domain and two nuclear export signal sequences containing hydrophobic residues are present in the PDZ domain.

LIMK1 exhibits tissue specific expression. It is predominantly expressed in brain but to a moderate extent in the heart and skeletal muscle. The least amount of LIMK1 expression was noted in the liver. LIMK1 is also expressed in lesser amounts in various human epithelial cell lines and haematopoetic cell lines.

LIMK1 is primarily localized in the cytoplasm but also transported to the nucleus. In the cytoplasm, LIMK1 is colocalized with microtubules, and actin at the focal adhesion, stress fiber and at the lamellipodia. In the mitotic cells, LIMK1 is localized to the centrosomes until early telophase and to the cleavage furrow during late telophase.

LIMK1 regulates organization of actin cytoskeleton through inactivating phosphorylation of the actin depolymerizing family (ADF) protein cofilin. LIMK1 phosphorylates cofilin at Serine, which inhibits actin depolymerization and results in accumulation of F actin. LIMK1 also regulates microtubule stability and assembly through phosphorylation of p25/TPPP (tubulin polymerization protein), which destabilizes microtubules. Activated LIMK1 associates with gamma-tubulin at the centrosome during mitotic phases. LIMK1 is a multifunctional protein and is involved in regulation of cell motility, cell cycle, cytokinesis and cellular morphology. LIMK1 also regulates neurite growth, synaptic stability, growth cone motility, axon formation through modulation of Golgi dynamics and neuronal differentiation.

LIMK1 has 50% identity overall and 70% identity in the kinase domain with another family member LIMK2. Although both proteins phosphorylate cofilin and regulate actin cytosketon reorganization current studies showed that LIMK2 has also different cellular function.

Hemizygous deletion of LIMK1 along with Elastin gene in a 1.5 MB deletion has been noted in patients with Williams-Beuren syndrome. Patients with Williams Syndrome exhibit impaired visuospatial constructive cognition possibly because of loss of LIMK1 gene.
SNP: A single nucleotide polymorphism of LIMK1 in a haplotype spanning Elastin gene has been linked to susceptibility of intracranial aneurysm (IA).