A full-length cDNA encoding putative reversibly glycosylated polypeptide (RGP) was cloned from cotton fiber cells using differential display combined with rapid amplification of the cDNA ends. The gene, designated GhRGP1, contains an open reading frame of 1080 bp encoding a protein of 359 amino acids which has 78-86% identity with other plant RGPs. Northern blot analysis showed that the gene is preferentially expressed in fiber cells and its transcripts are abundant both at the primary cell wall elongation stage and at the later stage of secondary cell thickening, suggesting that GhRGP1 may be involved in non-cellulosic polysaccharide biosynthesis of the plant cell wall.