diff --git a/v2/service/convert.go b/v2/service/convert.go
index bf2c3a2..2ced953 100644
--- a/v2/service/convert.go
+++ b/v2/service/convert.go
@@ -199,3 +199,29 @@ func RequestMetaHeaderFromGRPCMessage(m *service.RequestMetaHeader) *RequestMeta
 
 	return r
 }
+
+func SignatureToGRPCMessage(s *Signature) *service.Signature {
+	if s == nil {
+		return nil
+	}
+
+	m := new(service.Signature)
+
+	m.SetKey(s.GetKey())
+	m.SetSign(s.GetSign())
+
+	return m
+}
+
+func SignatureFromGRPCMessage(m *service.Signature) *Signature {
+	if m == nil {
+		return nil
+	}
+
+	s := new(Signature)
+
+	s.SetKey(m.GetKey())
+	s.SetSign(m.GetSign())
+
+	return s
+}
diff --git a/v2/service/service.go b/v2/service/service.go
index 39557ee..1a1e0a7 100644
--- a/v2/service/service.go
+++ b/v2/service/service.go
@@ -1,9 +1,5 @@
 package service
 
-import (
-	service "github.com/nspcc-dev/neofs-api-go/v2/service/grpc"
-)
-
 type Signature struct {
 	key, sign []byte
 }
@@ -315,29 +311,3 @@ func (r *RequestMetaHeader) StableSize() int {
 	// TODO: do not use hack
 	return RequestMetaHeaderToGRPCMessage(r).Size()
 }
-
-func SignatureToGRPCMessage(s *Signature) *service.Signature {
-	if s == nil {
-		return nil
-	}
-
-	m := new(service.Signature)
-
-	m.SetKey(s.GetKey())
-	m.SetSign(s.GetSign())
-
-	return m
-}
-
-func SignatureFromGRPCMessage(m *service.Signature) *Signature {
-	if m == nil {
-		return nil
-	}
-
-	s := new(Signature)
-
-	s.SetKey(m.GetKey())
-	s.SetSign(m.GetSign())
-
-	return s
-}