Alpha-keratin Alpha-keratin Alpha-keratin, or α-keratin, is a type of keratin found in mammals. This protein is the primary component in hairs, horns, nails and the epidermis layer of the skin. α-keratin is a fibrous structural protein, meaning it is made up of amino acids that form a repeating secondary structure. The secondary structure of α-keratin is very similar to that of a traditional protein α-helix and forms a coiled coil. Due to its tightly wound structure, it can function as one of the strongest biological materials and has various uses in mammals, from predatory claws to hair for warmth. α-keratin is
Outer plexiform layer Outer plexiform layer The outer plexiform layer (external plexiform layer) is a layer of neuronal synapses in the retina of the eye. It consists of a dense network of synapses between dendrites of horizontal cells from the inner nuclear layer, and photoreceptor cell inner segments from the outer nuclear layer. It is much thinner than the inner plexiform layer, where amacrine cells synapse with retinal ganglion cells. The synapses in the outer plexiform layer are between the rod cell endings or cone cell branched foot plates and horizontal cells. Unlike in most systems, rod and cone cells release neurotransmitters when