Catecholamines up

Catecholamines up (Catsup) is a dopamine regulatory membrane protein that functions as a zinc ion transmembrane transporter (orthologous to ZIP7), and a negative regulator of rate-limiting enzymes involved in dopamine synthesis and transport: Tyrosine hydroxylase (TH), GTP Cyclohydrolase I (GTPCH), and Vesicular Monoamine Transporter (VMAT) in Drosophila melanogaster.

Catsup plays a significant role in zinc ion transmembrane transport, and the mutations in Catsup gene can lead to abnormal accumulation of membrane proteins, such as Notch, decreased Notch signalling, increase in levels of apoptosis, and induce of ER stress response. Additionally, Catsup plays an important role in regulation of dopamine synthesis, and the mutations in Catsup gene can lead to hyperactivity of Catsup-regulated enzymes TH, GTPCH, and VMAT, as well as to increases in dopamine (DA) and tetrahydrobiopterin (BH₄) levels.