The nucleotide sequence of a 6 kb fragment encoding the main late proteins (p14, p38 and p24) of actinophage VWB was obtained. Sequence comparison of the encoded proteins with those filed in databases indicated that the phage VWB main late proteins were all novel. A search for special motifs revealed that p14 (13.3 kDa) has a P-loop sequence commonly found in ATP- and GTP-binding proteins. This observation might indicate that p14 is important for ATP-driven DNA translocation during encapsidation of VWB phage DNA into the phage head. Furthermore, the polypeptide ORF2 (26.9 kDa) has an unusual primary structure consisting of 3 stretches of acidic amino acid residues and a glycine/arginine rich C-terminal end. From comparison with other proteins including the bacteriophage T4 prohead core component and from the data of special motif analysis the ORF2 gene product is probably involved in prohead core formation.