Differential expression of mouse laminin gamma 2 and gamma 2*chain transcripts

Laminins are large heterotrimeric basement membrane proteins that consist o f alpha, beta, and gamma chains. We have previously shown that the human ga mma 2 and gamma 2* transcripts result from the alternative use of the LAMC2 gene 3'-end exons. To explore the biological significance of the alternati ve gamma 2 transcripts, we isolated the cDNA coding for the mouse laminin g amma 2* transcript, characterized the 3'-end of the murine LAMC2 gene, and studied the expression of alternative gamma 2 transcripts in several mouse tissues. The sequence reported here is the first one containing a full-leng th gamma 2* 3'-UTR from any species. The mouse gamma 2* transcript is 4110 bases and encodes a putative polypeptide of 1110 amino acids. This polypept ide lacks the C-terminal cysteine residue thought to be important fur heter otrimer formation. The mouse gamma 2* transcript was found to be expressed in several tissues by polymerase chain reaction (PCR), but at very low leve ls. The dearest signals were obtained on embryonic day 7, and in heart and testis of adult tissues. When the laminin gamma 2* transcript expression pa ttern was compared with that of the gamma 2 chain, a similar tissue distrib ution was observed. There was, however, a significant difference in express ion levels. The longer gamma 2 transcript was found to be much more abundan t than the shorter gamma 2* variant.