Primary structure of bovine collectin-43 (CL-43). Comparison with conglutinin and lung surfactant protein-D.
Collectin-43 (CL-43) is a bovine serum protein that is composed of subunits of three identical chains, each of which contains a collagen region and a C-type carbohydrate recognition domain; thus, CL-43 belongs to the collectins (group III of the C-type lectins). We have derived the complete primary sequence of CL-43 using partial protein sequencing, cDNA cloning, and reverse transcription-polymerase chain reaction techniques. The primary sequence of CL-43 shows that it contains an N-terminal region of 28 residues, followed by a collagenous domain of 38 repeats of Gly-Xaa-Yaa and then a C-terminal section of 159 residues, containing a short "neck" region and the carbohydrate recognition domain with the conserved residues found in all C-type lectins. The amino acid sequence of CL-43 showed 74% identity to bovine conglutinin and 70% identity to bovine lung surfactant protein D (SP-D), but the collagen region is considerably shorter than the 57 Gly-Xaa-Yaa triplets found in conglutinin and SP-D. Northern blot analysis showed that CL-43 was only synthesized in bovine liver, with no detectable signal in a variety of other bovine tissues, including lung. No cross-hybridizing signals were detected in mRNA from sheep, human, rat, or mouse liver. Since CL-43 and conglutinin have only been detected in members of bovidae, it is probable that an ancestral gene of these two proteins was first derived from a SP-D-like gene, and that this ancestral gene duplicated during evolution.
Lim
B L
BL
Department of Biochemistry, University of Oxford, United Kingdom.
Willis
A C
AC
Reid
K B
KB
Lu
J
J
Laursen
S B
SB
Jensenius
J C
JC
Holmskov
U
U
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001798:Blood Proteins / Q000737:chemistry*; D002417:Cattle; D003001:Cloning, Molecular; D037222:Collectins; D018076:DNA, Complementary / Q000378:metabolism; D006023:Glycoproteins / Q000737:chemistry*; D037102:Lectins / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification; D008099:Liver / Q000378:metabolism*; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D016133:Polymerase Chain Reaction; D037663:Pulmonary Surfactant-Associated Protein D; D011663:Pulmonary Surfactants / Q000737:chemistry*; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid; D012712:Serum Globulins / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification
D001798:Blood Proteins; D037222:Collectins; D018076:DNA, Complementary; D006023:Glycoproteins; D037102:Lectins; D015345:Oligonucleotide Probes; D037663:Pulmonary Surfactant-Associated Protein D; D011663:Pulmonary Surfactants; D011994:Recombinant Proteins; D012712:Serum Globulins; C024014:conglutinin; C086954:collectin-43 protein, bovine