lin-12(
n941) is an EMS-induced
lin-12 allele that our lab uses as the canonical null allele for genetic studies. This allele contains an amber stop codon in the eighth EGF-like motif (amino acid W400STOP). This observation suggests that
lin-12(
n941) is a molecular null allele.
lin-12(
n941) causes a highly penetrant 2 AC defect and other cell fate transformations as described in Greenwald et al. (1983). Note that in the presence of
smg-1, the
lin-12(
n941) allele causes an embryonic lethal phenotype, probably as a result of a dominant-negative effect of the truncated extracellular domain (Hilary Wilkinson, personal communication.)
lin-12(
n302ar220) behaves like a null allele; it contains a UV/TMP-induced lesion,
ar220, a small deletion in the extracellular domain that creates a frameshift mutation in the fourth EGF-like motif. We have not examined the effect of
smg-1 on this allele.
lin-12(
n676n930) is an EMS-induced hypomorphic allele that we have used for many genetic studies in our lab. This allele contains a missense mutation in the second EGF-like repeat (amino acid C138Y). The genetic properties of this allele have been described in detail in Sundaram and Greenwald (1993a). Sequence changes associated with
lin-12(
n302),
lin-12(
n676) and most other
lin-12(d) mutations were published in Greenwald and Seydoux (1990).