CLIPAssociated Proteins (CLASPs) is specifically binding to microtubules of microtubule associated proteins (MAPS),involved in mediating the structure and function of microtubules,and play key roles during cell formation and cell elongation.A new CLASP gene was obtained from Gossypium hirsutum L.by electronic cloning and reversetranscription polymerase chain reaction (RTPCR) technology.Sequence analysis showed that GhCLASP1 belongs to the CLASP gene family,the full length ORF of GhCLASP1 is 4 188 bp,encoding 1 395 amino acids.GhCLASP1 has one HEAT domain and two CLASPN structures.The phylogenetic analysis of homologue CLASP proteins of other plants showed that GhCLASP1 had a close relationship with TcCLASP of Theobroma cacao.Realtime quantitative reverse transcription PCR (qRTPCR) showed that GhCLASP1 was expressed in root,stem,leaf,petal and fiber at different development periods.The highest expression of the GhCLASP1 was observed in the secondary period of the cotton fiber wall thick (27 day post anthesis) and suggesting that GhCLASP1 might play an important role in the formation of secondary wall synthesis of cotton fiber.Transient expression system of the Nicotiana benthamiana leaves was used to analyze subcellular localization,and showed that GhCLASP1 might locate in the cell membrane.This study proved a foundation for studying the functions of CLASP genes in fiber development.