Molecular cloning and characterization of a novel receptor protein tyrosine kinase from human placenta.
Using a polymerase chain reaction-based approach we have isolated and characterized a cDNA (HPK-6) from human placental RNA encoding a novel receptor protein tyrosine kinase. This receptor tyrosine kinase has a unique extracellular domain, with an immunoglobulin-like domain at the amino terminus followed by three EGF-like cysteine repeats and three fibronectin type III repeats, giving the HPK-6 gene extracellular domain a novel combination of structural motifs. A comparison of the HPK-6 sequence with other receptor tyrosine kinases shows that the HPK-6 gene is the human homolog of the murine tek gene and very closely related to the recently described receptor tyrosine kinase tie. The HPK-6 gene is expressed predominantly in placenta and lung, with a lower level in umbilical vein endothelial cells, brain and kidney. The HPK-6 cDNA, when transfected into COS-7 cells, encodes a 140-kDa protein with in vitro kinase activity.
Immunex Corporation, Seattle, Washington 98101.
S F
SF
Ziegler
T A
TA
Bird
J A
JA
Schneringer
K A
KA
Schooley
P R
PR
Baum
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D005260:Female; D015870:Gene Expression; D006801:Humans; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000235:genetics; D010920:Placenta / Q000201:enzymology*; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011505:Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D011506:Proteins / Q000235:genetics; D011817:Rabbits; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics*
D010750:Phosphoproteins; D011506:Proteins; D011956:Receptors, Cell Surface; D004247:DNA; D011505:Protein-Tyrosine Kinases