Characterization of gamma-crystallins from a hybrid teleostean fish: multiplicity of isoforms as revealed by cDNA sequence analysis.
gamma-Crystallins were isolated and characterized from the eye lenses of a hybrid species belonging to the teleostean fish. Isoelectric focusing of gamma-crystallin fraction obtained from gel-permeation chromatography revealed that it consists of multiple charge isomers of a protein species with a molecular mass of about 20 kDa. To facilitate the cloning of gamma-crystallin gene, cDNA was constructed from the poly(A)+mRNA isolated from fresh lenses, and amplification by polymerase chain reaction (PCR) was carried out to obtain cDNA encoding multiple gamma-crystallins. Sequencing five of more than 10 positive clones revealed that a multiplicity of isoforms exists in the gamma-crystallin class of teleostean lenses. Comparison of protein sequences encoded by these multiple cDNAs with those published sequences of gamma-crystallins from bovine, mouse an carp lenses indicated that there is about 70-80% sequence homology between different species of piscine species whereas only 50-60% is found between mammals and fishes. Structural analysis of these gamma-crystallins with high methionine contents (11-16%) suggests that there are two major subclasses of piscine gamma-crystallins, i.e. gamma M 1 and gamma M 2, existed long before the appearance of mammalian gamma-crystallin with low methionines.
Laboratory of Crystallin Research, National Taiwan University, Taipei.
F M
FM
Pan
W C
WC
Chang
Y K
YK
Chao
S H
SH
Chiou
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002347:Carps / Q000235:genetics; D002417:Cattle; D003001:Cloning, Molecular; D003433:Crosses, Genetic; D003459:Crystallins / Q000737:chemistry / Q000235:genetics*; D017931:DNA Primers; D005260:Female; D005399:Fishes / Q000235:genetics*; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family; D010471:Perches / Q000235:genetics; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis; D017386:Sequence Homology, Amino Acid
D003459:Crystallins; D017931:DNA Primers; D012333:RNA, Messenger