Table III.

Processing Efficiency and Overall Export Efficiency of a-Factor

		Processing efficiency* ‡		Export efficiency* §
MFA1		11%		8%
MFA2		30%		14%

^* Values were calculated from cells expressing chromosomal MFA1 or MFA2 only (SM2891 and SM2892, respectively) and are averaged from Phosphorimager analysis of two gels, one of which is shown in Fig. 8 A. The calculations are based on the assumption that each a-factor molecule contains only a single radiolabeled residue ([³⁵S]cysteine). Even if some metabolic conversion of [³⁵S]cysteine to [³⁵S]methionine could occur, the overall values would not be altered significantly; only P1, which contains an NH₂-terminal Met, would be affected.  

^‡ The “processing efficiency” is the percentage of a-factor precursor that is initially synthesized within a 5-min pulse [P1 + P2]_0′ that is ultimately converted after 15 min to mature a-factor [M(I) + M(E)]_15′.  

^§ The “export efficiency” is the percentage of a-factor initially synthesized [P1 + P2 + M(I) + M(E)]_0′ that is ultimately exported to culture fluid as mature a-factor [M(E)]_30′.