Bovine alpha 1-microglobulin/bikunin. Isolation and characterization of liver cDNA and urinary alpha 1-microglobulin.
cDNA coding for alpha 1-microglobulin, an immunoregulatory plasmaprotein, was isolated from bovine liver. The sequence of a total of 1258 nucleotides revealed an open reading frame of 352 amino acids. This included alpha 1-microglobulin, 182 amino acids, and bikunin, the light chain of the plasmaprotein inter-alpha-inhibitor, 147 amino acids. The two proteins were connected by a basic tetrapeptide, R-A-R-R, which conforms to the consensus sequence recognized by endoproteolytic cleavage enzymes. The deduced amino acid sequence showed a high degree of identity with alpha 1-microglobulin and bikunin sequences from other species, and the alpha 1-microglobulin part displayed sequence motifs typical for members of the lipocalin protein superfamily. A single alpha 1-microglobulin/bikunin mRNA with a size of around 1300 nt was found in bovine liver. The mature alpha 1-microglobulin protein was isolated from bovine urine, and partly characterized. It was found to be a globular molecule with an apparent molecular weight of 23,300, containing one N-linked and at least on O-linked oligosaccharide, one intra-chain disulfide bridge and an electrophoretic heterogeniety with a pI-value of 4.1-5.2.
Lindqvist
A
A
Department of Cell and Molecular Biology, Lund University, Sweden. annikalindqvist@medkem.lu.se
Akerström
B
B
D000510:Alpha-Globulins / Q000235:genetics* / Q000302:isolation & purification; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle / Q000235:genetics*; D006224:Cricetinae; D018076:DNA, Complementary / Q000235:genetics* / Q000302:isolation & purification; D005260:Female; D005796:Genes; D005849:Gerbillinae; D006023:Glycoproteins / Q000235:genetics*; D006031:Glycosylation; D006168:Guinea Pigs; D006801:Humans; D008099:Liver / Q000378:metabolism*; D008562:Membrane Glycoproteins; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016366:Open Reading Frames; D011247:Pregnancy; D011499:Protein Processing, Post-Translational; D011817:Rabbits; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014360:Trypsin Inhibitor, Kunitz Soybean; D014556:Urine / Q000737:chemistry*
D000510:Alpha-Globulins; D018076:DNA, Complementary; D006023:Glycoproteins; D008562:Membrane Glycoproteins; C109148:SPINT2 protein, human; C016001:alpha-1-microglobulin; D014360:Trypsin Inhibitor, Kunitz Soybean