Glutamine
Glutamine is the most abundant naturally occurring, nonessential amino acid in the human body, and one of the few amino acids that can directly cross the blood–brain barrier. Humans obtain glutamine through catabolism of proteins in foods they eat. In states where tissue is being built or repaired, like growth of babies, or healing from wounds or severe illness, glutamine becomes conditionally essential.
Multiple Epidermal Growth Factor-like Domains 8
MEGF8 is composed of either 2845 amino acids (Isoform 1) or 2778 amino acids (Isoform 2). Isoform 2 undergoes a 67 amino acid removal from 700-766, which accounts for its shortened length; otherwise, the two isoforms are identical. Using SAPS, a Statistical Analysis of Protein Sequence software, amino acid bias was able to be determined. Isoform one is rich in cysteine and glycine, and deficient in isoleucine and lysine. Isoform 2 of MEGF8 was found to have very high levels of cysteine, moderately high levels of glycine, and low levels of isoleucine and lysine.
The high levels of cysteine residues contributes to the numerous disulfide bonds found in the mature protein's folded structure. Overall, MEGF8 has a pH between 6.4 and 7.0, depending on the organism's sequence. Human MEGF8's pH is 6.4. This nearly neutral pH enables the protein to fold properly and inhibits denaturation. The twenty most conserved amino acids, found through a multiple sequence alignment of 20 orthologs, were found to be located in the CUB and transmembrane domains.