DYNEIN HEAVY CHAIN-RELATED POLYPEPTIDES ARE ASSOCIATED WITH ORGANELLES IN POLLEN TUBES OF NICOTIANA-TABACUM

It is known that pollen tubes contain two high molecular weight polype ptides which share some biochemical and immunological properties with dynein heavy chains. This paper reports data on the subcellular locali zation of the two dynein heavy chain-related polypeptides during polle n tube growth. Immunofluoresence studies using a purified antibody (Dy -1) raised against a synthetic peptide reproducting the P-loop conserv ed sequence of dynein heavy chains showed spot-like structures, with a characteristic distribution pattern that depended on the tube length. Biochemical evidence confirmed the presence of dynein heavy chain-rel ated bands in the pollen tube membrane fraction. The association of pr oteins carrying dynein heavy chain-related polypeptides to cell membra nes was affected by detergent (Triton x 100), whereas other stripping agents, like NaCl and Na2CO3. did not significantly influence the inte raction of dynein heavy chain-related doublet with their cytoplasmic t argets. These data suggest that dynein heavy chain-related polypeptide s associate with membranous organelles within the vegetative cell of N icotiana tabacum pollen tubes, implying their involvement in the cytop lasmic distribution of these organelles.