Here's why:

* ER signal sequence: This is a short stretch of amino acids at the N-terminus of a protein that acts like a "zip code" directing it to the endoplasmic reticulum (ER). The ER is a crucial organelle involved in protein folding, modification, and transport.

* Cytoplasmic synthesis: All proteins are initially synthesized by ribosomes in the cytoplasm.

* No signal sequence, no ER entry: Without an ER signal sequence, the protein won't bind to the ER membrane and won't be translocated into the ER lumen.

* Remain in the cytoplasm: Consequently, the protein will stay in the cytoplasm where it may function or be targeted to other cellular locations.

Important Note: Some proteins that lack an ER signal sequence may have different targeting signals that direct them to other cellular compartments like mitochondria, chloroplasts, or the nucleus.