Structure of the SMYD2-PARP1 Complex Reveals Both Productive and Allosteric Modes of Peptide Binding.

Allosteric regulation allows proteins to dynamically respond to environmental cues by modulating activity at sites away from the catalytic center. Despite its importance, the SET-domain protein lysine methyltransferase superfamily has been understudied. Here, we present four crystal structures of SMYD2, a unique family member with a MYND domain.

Early Divergence of the C-Terminal Variable Region of Troponin T Via a Pair of Mutually Exclusive Alternatively Spliced Exons Followed by a Selective Fixation in Vertebrate Heart.

Troponin T (TnT) is the thin filament anchoring subunit of troponin complex and plays an organizer role in the Ca-regulation of striated muscle contraction. From an ancestral gene emerged ~ 700 million years ago in Bilateria, three homologous genes have evolved in vertebrates to encode muscle type-specific isoforms of TnT. Alternative splicing variants of TnT are present in vertebrate and invertebrate muscles to add functional diversity.

Evolution of Flight Muscle Contractility and Energetic Efficiency.

The powered flight of animals requires efficient and sustainable contractions of the wing muscles of various flying species. Despite their high degree of phylogenetic divergence, flight muscles in insects and vertebrates are striated muscles with similarly specialized sarcomeric structure and basic mechanisms of contraction and relaxation. Comparative studies examining flight muscles together with other striated muscles can provide valuable insights into the fundamental mechanisms of muscle contraction and energetic efficiency.

The glutamic acid-rich-long C-terminal extension of troponin T has a critical role in insect muscle functions.

The troponin complex regulates the Ca activation of myofilaments during striated muscle contraction and relaxation. Troponin genes emerged 500-700 million years ago during early animal evolution. Troponin T (TnT) is the thin-filament-anchoring subunit of troponin.

Invertebrate troponin: Insights into the evolution and regulation of striated muscle contraction.

The troponin complex plays a central role in regulating the contraction and relaxation of striated muscles. Among the three protein subunits of troponin, the calcium receptor subunit, TnC, belongs to the calmodulin family of calcium signaling proteins whereas the inhibitory subunit, TnI, and tropomyosin-binding/thin filament-anchoring subunit, TnT, are striated muscle-specific regulatory proteins. TnI and TnT emerged early in bilateral symmetric invertebrate animals and have co-evolved during the 500-700 million years of muscle evolution.