A U wave as seen on ECG. An electrocardiogram of an 18-year-old man showing U waves, most evident in lead V3. The U wave is a wave on an electrocardiogram that is not always seen. It is typically small, and, by definition, follows the T wave. U waves are thought to represent repolarization of the papillary muscles or Purkinje fibers.
HCP is caused by mutations in the CPOX gene, which codes for the enzyme coproporphyrinogen oxidase. This enzyme is responsible for the sixth step in the heme biosynthetic pathway, converting coproporphyrinogen III to protoporphyrinogen IX.
Summary. This gene encodes a member of the glyceraldehyde-3-phosphate dehydrogenase protein family. The encoded protein has been identified as a moonlighting protein based on its ability to perform mechanistically distinct functions. GAPDH was identified as a binding protein on the plasma membrane of CEM-SS leukemia cells for Bt18 parasporal protein. 2  The study demonstrated that GAPDH is reliable as reference gene for quantitative gene expression analysis in human diploid fibroblasts.