Unusual electrophoretic mobility of maize Hrgp mRNA

Hybridisation bands of mobility lower than expected appear in RNA blot anal ysis performed using total maize RNA hybridised with an hydroxyproline-rich glycoprotein (HRGP) cDNA probe. This behaviour has previously been observe d and some authors have proposed that these bands could be transcripts of g enes coding for highly similar genes. However, other data indicate that a s ingle gene coding for HRGP exists in the maize genome. Here, we show that s ome of the mRNA molecules hybridising with the Hrgp probe migrate in agaros e gel electrophoresis at a lower velocity than expected. The relative inten sity of these low-mobility bands depends on the abundance of the Hrgp mRNA molecules loaded in the electrophoresis gels, a result confirmed by using t wo-dimensional gel electrophoresis. We propose that these hybridisation ban ds may be the product of different secondary structures or multimers of the 1.5-kb Hrgp mRNA probably due to high G+C content and the highly repetitiv e sequence of these molecules. (C) Elsevier, Paris.