Isolation and characterization of cDNAs encoding the heavy chain of human inter-. cap alpha. -trypsin inhibitor (I. cap alpha. TI): unambiguous evidence for multipolypeptide chain structure of I. cap alpha. TI
Human inter-..cap alpha..-trypsin inhibitor (I..cap alpha..TI) is a plasma glycoprotein of M/sub r/ 180,000, which has been described as a single polypeptide chain. Recently, however, the authors proposed that I..cap alpha..TI might be composed of a heavy (H) chain (M/sub r/ = 95,000) and a light (L) chain (M/sub r/ = 40,000) synthesized by two separate mRNAs. In the present study they have characterized cDNAs for the H chain of I..cap alpha..TI. These cDNAs collectively covered two sequences (977 and 1450 base pairs in length) with single open reading frames. The deduced amino acid sequences were highly homologous to each other and well matched with partial amino acid sequences obtained from purified serum I..cap alpha..TI. RNA blot analyses of liver RNAs with H- or L-chain cDNAs as probes clearly identified two distinct mRNAs of 3.3 and 1.3 kilobases, which correspond to H or L chain, respectively. Poly(A)/sup +/ RNAs hybrid-selected with H-chain cDNAs coded for polypeptide chains of M/sub r/ 90,000-95,000. These results unambiguously establish that I..cap alpha..TI is made of multipolypeptides, possibly including one H and two L chains. The H chain contains potential calcium-binding sites and also regions homologous to the proposed reactive site for thiolproteinase inhibitors. These data indicate that I..cap alpha..TI is a complex, multifunctional protein. mRNAs for both the H and L chains were found only in liver.
- Research Organization:
- Institut National de la Sante et de la Recherche Medicale, Saint-Etienne-du-Rouvray (France)
- OSTI ID:
- 6408987
- Journal Information:
- Proc. Natl. Acad. Sci. U.S.A.; (United States), Vol. 84:23
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ENZYME INHIBITORS
AMINO ACID SEQUENCE
RECOMBINANT DNA
DNA SEQUENCING
GLUCOPROTEINS
HYBRIDIZATION
LIVER
MAN
MESSENGER-RNA
NUCLEOTIDES
RABBITS
SULFUR 35
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CARBOHYDRATES
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
DNA
EVEN-ODD NUCLEI
GLANDS
GLYCOPROTEINS
ISOTOPES
LIGHT NUCLEI
MAMMALS
MOLECULAR STRUCTURE
NUCLEI
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANS
PRIMATES
PROTEINS
RADIOISOTOPES
RNA
SACCHARIDES
STRUCTURAL CHEMICAL ANALYSIS
SULFUR ISOTOPES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques