Developmental and tissue-specific expression of alpha 1-microglobulin mRNA in the rat.
A rat liver cDNA library was constructed in the lambda gt11 expression vector. Three clones expressing alpha 1-microglobulin, an immunosuppressive plasma protein, were detected by screening with rabbit antiserum against rat alpha 1-microglobulin. The alpha 1-microglobulin activity from one of the clones, 6b, was confirmed with monoclonal antibodies in a solid phase radioimmunoassay. The nucleotide sequence of the fragment (165 base pairs) was determined, and the translated amino acid sequence (55 amino acids) showed a 75% homology to human alpha 1-microglobulin (position 122-176). Southern blots of restriction endonuclease-digested rat DNA indicated two distinct genes with alpha 1-microglobulin homology when probed with radioactive cDNA fragment from clone 6b. Northern blots showed the presence of a single mRNA species in rat liver, and the level was low in 1-month-old animals, increased to reach a maximum during adulthood (3 months), and decreased with aging (12 months). The alpha 1-microglobulin concentration in rat serum showed the same age dependence between 1 and 12 months, with the highest values at 3 months. Embryonic development (8.5-day to 17.5-day) was studied using total fetal RNA, and expression of alpha 1-microglobulin mRNA was detected in low amounts only at day 15.5. alpha 1-Microglobulin mRNA levels, studied by an RNA dot blot assay, were high in liver and kidney, low in brain and testis, and none were found in hypothalamus and spleen cells.
D000375:Aging; D000510:Alpha-Globulins / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D005333:Fetus; D006801:Humans; D008099:Liver / Q000254:growth & development* / Q000378:metabolism; D008297:Male; D012333:RNA, Messenger / Q000235:genetics*; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution
D000510:Alpha-Globulins; D012333:RNA, Messenger; C016001:alpha-1-microglobulin; D004247:DNA