Glutamine
In human blood, glutamine is the most abundant free amino acid.
HIPK2
The HIPK2 protein is 1198 amino acids in length and has a molecular weight of 130.97 kilodaltons. The most abundant amino acids in the protein are serine, threonine and alanine, which make up approximately 30 percent of the proteins total amino acid count. The structure of the protein in its native form is unstable. The protein is made up of several regions which directly relate to its function, regulation, and localization. The protein kinase domain is 330 amino acids long and is located near the N-terminus of the protein. In addition to its kinase domain, HIPK2 has two nuclear localization signals, a SUMO interaction motif, an auto-inhibitory domain a transcriptional co-repression domain, and several interaction domains, including one for p53. While there are signals targeting HIPK2 to nuclear speckles, there is also a speckle retention sequence that causes HIPK2 to remain in the nuclear speckles. The auto-inhibitory domain, which contains an ubiquitylation site at the K1182 residue is located at the C-terminus.