Elastin since they become crosslinked into elastin fibres immediately after their synthesis by the cell and during their export into the extracellular matrix. Each tropoelastin consists of a string of 36 small domains, each weighing about 2 kDa in a random coil conformation. The protein consists of alternating hydrophobic and hydrophilic domains, which are encoded by separate exons, so that the domain structure of tropoelastin reflects the exon organization of the gene. The hydrophilic domains contain Lys-Ala (KA) and Lys-Pro (KP) motifs that are involved in crosslinking during the formation of mature elastin. In the KA domains, lysine residues occur as
Alpha-keratin large variation in α-keratin structures found in mammals. α-keratin synthesis begins near focal adhesions on the cell membrane. There, the keratin filament precursors go through a process known as nucleation, where the keratin precursors of dimers and filaments elongate, fuse, and bundles together. As this synthesis is occurring, the keratin filament precursors are transported by actin fibers in the cell towards the nucleus. There, the alpha-keratin intermediate filaments will collect and form networks of structure dictated by the use of the keratin cell as the nucleus simultaneously degrades. However, if necessary, instead of continuing to grow, the keratin complex will