A cDNA library from lamprey liver was constructed in pBR322 and screened with a synthetic mixed oligonucleotide probe, the sequence of which was based on a partial amino acid sequence of the lamprey fibrinogen gamma chain determined by conventional procedures. Among the positive clones was one containing a 600-base insert that covered the carboxy-terminal third of the chain and another with a 1950-base insert that stretched more than full length. The two inserts were sequenced by the Maxam-Gilbert procedure. The DNA sequencing was corroborated by reference to the amino acid sequences of five cyanogen bromide peptides that compose the carboxy-terminal 130 amino acids, as well as to a number of tryptic peptides from elsewhere in the molecule. The clone with the smaller insert (6G) contained 594 nucleotides (not counting G and C tails), 435 of which are coding and correspond to residues 264-408 of the gamma chain. The remaining 159 nucleotides included the terminator codon followed by a noncoding segment. The larger clone (2E) coded for 408 amino acids that could be readily aligned with the 411-residue human gamma chain. A 24-residue signal peptide adjacent to the proposed amino terminal was also inferred. The amino acid sequence of the fibrinogen gamma chain has been differentially conserved during evolution, the lamprey and human sequences being more than 70% identical in certain key regions but dropping to less than 25% in other sections, including the segment thought to be a part of the "coiled coils". Overall, the resemblance amounts to 50% identity. Of the 10 cysteines found in mammalian chains, 9 are at identical positions, but the tenth, which in mammalian fibrinogens is a part of the interdimeric bridging, is absent in the lamprey.

Porcine CFL2b gene play an important role in the muscle development and myofibrillar formation in pig. To explore whether CFL2b expression affects muscle fiber trait, the porcine CFL2b full-length cDNA was amplified using homology based cDNA cloning and SMART RACE. Then the full length cDNA of porcine CFL2b was inserted into pEGFP-N1 and transfected into C2C12 cells. The cells stably expressing CFL2b were selected by G418. We examined the expression of MyHC 2x, MyHC 2b and MyHC1/slow in C2C12 cells stably expressing CFL2b. The results showed that the level of MyHC 2x and MyHC 2b mRNA were dramatically increased compared with control cells, while the level of MyHC1/slow mRNA is not changed. To identify the transcription events of CFL2b, the porcine CFL2b mRNA was detected by Northern blotting, two transcripts, long transcript (3,012 bp) and short transcript (1,466 bp) were found in porcine skeletal muscles. The nucleotide sequence of CFL2b shares 88.1 and 74.9% homology with the CFL2b gene in human and mouse. The deduced amino acid sequence of CFL2b (166 amino acids) in pig shares 100, 99.1% identity with the CFL2b in human and mouse, respectively. Taken together, our research revealed that porcine CFL2b may be involved in the regulation muscle fiber trait by affecting the expression of MyHC.