The signal sequence of the p62 protein of Semliki Forest virus is involved in initiation but not in completing chain translocation

Construction of pGEM SFV d-4. This plasmid was constructed by ligatiag three fragments together. The first one was the major part of pGEM1, cut just after the promoter region with Hind III and Barn HI. The second fragment (Hind I~-Xho I) was isolated from the plasmid pSVS-SFV . This fragment contains the sequences encoding the capsid and the NH2-terminal part of the 1962 protein of SFV. The third fragment was obtained by cleaving plasmid pL1 SFV d-4 (see below) with Xho I and Barn HI and isolating the fragment containing the 3' part of the coding sequence for the p62 protein. However, it should be noted that in the d-4 version there is an exchange of 15 codons at the 3' end of the 1062 gene for six aberrant ones. The corresponding p62 protein variant is called 1962 d-4 (see Fig. 1 ). It should also be mentioned that pL1 SFV d-4 has been derived from pL1 SFV d-9, (Cutler and Garoff, 1986 ) by exchanging the Xho I-Cla I region containing the 3' part of the p62 coding region with the similar fragment from pSV2 SFV d-4. This latter plasmid is described in Garoff et al. (1983) .