Involucrin

Involucrin is a is_associated_with::protein component of human skin and in humans is encoded by the IVL is_associated_with::gene. In binding the protein is_associated_with::loricrin, involucrin contributes to the formation of a cell envelope that protects is_associated_with::corneocytes in the skin.

Gene
This gene is mapped to 1q21, among calpactin I light chain, trichohyalin, is_associated_with::profillaggrin, is_associated_with::loricrin, and is_associated_with::calcyclin.

Function
Involucrin is a highly reactive, soluble, is_associated_with::transglutaminase substrate is_associated_with::protein present in is_associated_with::keratinocytes of epidermis and other is_associated_with::stratified squamous epithelia. It first appears in the cell is_associated_with::cytosol, but ultimately becomes cross-linked to is_associated_with::membrane proteins by transglutaminase thus helping in the formation of an insoluble envelope beneath the plasma membrane functioning as a is_associated_with::glutamyl donor during assembly of the cornified envelope.

Involucrin is synthesised in the is_associated_with::stratum spinosum and cross linked in the is_associated_with::stratum granulosum by the is_associated_with::transglutaminase enzyme that makes it highly stable. Thus it provides structural support to the cell, thereby allowing the cell to resist invasion by micro-organisms.

is_associated_with::Apigenin, a plant-derived is_associated_with::flavanoid that has significant promise as a is_associated_with::skin cancer is_associated_with::chemopreventive agent, has been found to regulate normal human keratinocyte differentiation by suppressing involucrin, and this is associated with reduced cell proliferation without is_associated_with::apoptosis.

Structure
Involucrin consists of a conserved is_associated_with::N-terminal region of about 75 is_associated_with::amino acid residues followed by two extremely variable length segments that contain is_associated_with::glutamine-rich is_associated_with::tandem repeats. The is_associated_with::glutamine residues in the tandem repeats are the substrate for the transglutaminase in the cross-linking reaction. The total size of the protein varies from 285 residues (in is_associated_with::dog) to 835 residues (in is_associated_with::orangutan).