Structural characterization of thymidine phosphorylase purified from human placenta.
Human thymidine phosphorylase (dThdPase) is thought to be identical to an angiogenesis factor, platelet-derived endothelial cell growth factor (PD-ECGF). However, the whole amino acid sequence of dThdPase is still unknown. N-terminal amino acid sequencing of dThdPase isolated from human placenta gave the sequence Ac-AALMTPGTGAPPAPG. Comparison with the sequence predicted from the PD-ECGF cDNA reveals that residues 2-16 of dThdPase are identical to that of PD-ECGF. If dThdPase and PD-ECGF are derived from the same gene, the primary translational product of dThdPase would be processed one amino acid from the translation-initiating methionine residue and Ala-2 acetylated. Since placental and platelet PD-ECGF is reported to be processed at Thr-6 and Ala-11, respectively, and the N-terminal end is not blocked, further study is needed to clarify the reason for this discrepancy and whether the difference in N-terminal sequence affects the physiological function of these molecules.
Miyadera
K
K
Institute for Cancer Research, Faculty of Medicine, Kagoshima University, Japan.
Dohmae
N
N
Takio
K
K
Sumizawa
T
T
Haraguchi
M
M
Furukawa
T
T
Yamada
Y
Y
Akiyama
S
S
D000595:Amino Acid Sequence; D001792:Blood Platelets / Q000378:metabolism; D005260:Female; D006801:Humans; D008969:Molecular Sequence Data; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D014176:Protein Biosynthesis; D011499:Protein Processing, Post-Translational; D017386:Sequence Homology, Amino Acid; D013939:Thymidine Phosphorylase / Q000235:genetics* / Q000302:isolation & purification*
D013939:Thymidine Phosphorylase