Production of a red blood cell's hemoglobin depends on mitochondrial heme 
synthesis. However, mature red blood cells are devoid of mitochondria and rely 
on glycolysis for ATP production. The molecular basis for the selective 
elimination of mitochondria from mature red blood cells remains controversial. 
Recent evidence suggests that clearance of both mitochondria and ribosomes, 
which occurs in reticulocytes following nuclear extrusion, depends on autophagy. 
Here, we demonstrate that Ulk1, a serine threonine kinase with homology to yeast 
atg1p, is a critical regulator of mitochondrial and ribosomal clearance during 
the final stages of erythroid maturation. However, in contrast to the core 
autophagy genes such as atg5 and atg7, expression of ulk1 is not essential for 
induction of macroautophagy in response to nutrient deprivation or for survival 
of newborn mice. Together, these data suggest that the ATG1 homologue, Ulk1, is 
a component of the selective autophagy machinery that leads to the elimination 
of organelles in erythroid cells rather that an essential mechanistic component 
of autophagy.