INDEPENDENT REGULATION OF FULL-LENGTH AND 5'-TRUNCATED PAS5 MESSENGER-RNAS IN SACCHAROMYCES-CEREVISIAE

Peroxisome assembly in Saccharomyces cerevisiae requires the products of several genes. In this report, the PAS5 gene has been characterized . The gene is on the left arm of chromosome X and encodes a polypeptid e with similarity to the mammalian peroxisome assembly factor-1 (PAF-1 ). Two different length transcripts are produced from the yeast PASS g ene. The longer mRNAs encompass an open reading frame, while the short er transcripts initiate 46-110 base pairs downstream of the first in-f rame AUG. The longer transcripts are induced four-fold on medium conta ining fatty acids as the sole carbon source, while the shorter transcr ipts are induced up to ten-fold on medium containing glycerol as a car bon source. The full-length coding sequence encodes a protein with a c alculated molecular weight of 30.7 kDa. A protein of 25 kDa could be t ranslated from the shorter transcripts and would lack a very acidic do main found in the amino-terminal extension of the longer protein. The common portion of the proteins is very basic; the calculated pI of the longer polypeptide is 9.02 and that of the shorter protein is 10.06. The PAS5 GenBank accession number is M86538.