And jewelry in the world, dating from

The Varna Necropolis, or Varna Cemetery, is a burial site in the western industrial zone of Varna, internationally considered one of the key archaeological sites in world prehistory. The oldest gold treasure and jewelry in the world, dating from 4,600 BC to 4,200 BC, was discovered at the site. Several prehistoric Bulgarian finds are considered no less old – the golden treasures of Hotnitsa, Durankulak, artifacts from the Kurgan settlement of Yunatsite near Pazardzhik, the golden treasure Sakar, as well as beads and gold jewelry found in the Kurgan settlement of Provadia – Solnitsata. However, Varna gold is most often called the oldest since this treasure is the largest and most diverse.

In molecular biology, calmodulin binding domain (CaMBD) is a protein domain found in small-conductance calcium-activated potassium channels (SK channels). These channels are independent of voltage and gated solely by intracellular Ca²⁺. They are heteromeric complexes that comprise pore-forming alpha-subunits and the Ca²⁺-binding protein calmodulin (CaM). CaM binds to the SK channel through the CaMBD, which is located in an intracellular region of the alpha-subunit immediately carboxy-terminal to the pore. Channel opening is triggered when Ca²⁺ binds the EF hands in the N-lobe of CaM. The structure of this domain complexed with CaM is known. This domain forms an elongated dimer with a CaM molecule bound at each end; each CaM wraps around three alpha-helices, two from one CaMBD subunit and one from the other.